Archive of Our Own ^beta

Chapter Text

Everything changed in a fateful event, in the original balance of time Kaigaku was not sent in the direction of the mount Nagumo mission.

With a swipe in the pendulum we're going to see what would change if Kaigaku went on mount Natagumo encountering Tanjiro and fighting a lower moon.

But before we go into that another event is going to be changed, the mission that Kaigaku took before the mount Natagumo.

His crow instructed him to go into a remote village. Some women started to be encountered with only their heads, Kaigaku arrived at the village and the first thing he noticed was that a little kid was being chased down being accused of theft.

“Stupid kid, can't even do it right.” Kaigaku muttered to himself looking at the scene with pity, Kaigaku himself is only wearing the slayer corps uniform, wearing a yellow magatama necklace, with his nichirin blade behind his back.

When the kid was close to getting caught in a flash Kaigaku disappeared from his location taking the kid into his arms and appearing into a distant alleyway, the kid stole a pouch of money that Kaigaku kept with himself.

He throws the kid in the ground without any type of care, the kid looks up at him with fear in his face. Kaigaku just looks at the kid with a snarl.

“Be a more sneaky kid, or better yet stop stealing next time nobody will protect you.” Kaigaku said tossing a pouch of money to the kid, this was his own money not the stolen one, after that he left the place without turning around only hearing the kid thanking him.

Returning to the streets he needs to discover the pattern of the killings so he went to the place where he saw the stealing happening, in there the same individuals are still talking confused with what happened a few minutes ago so Kaigaku decided to go talk with them.

“Gentleman, I believe the kid stole this from you.” Kaigaku said, getting in close proximity with the pouch of money in his left hand, the eyes of the man who lost the money light up as he recognised the pouch thanks to a crest marked into it.

“Thank you boy! You just saved my life, I'm Gatou, a traveling merchant.” The man Gatou said he was then expecting Kaigaku to introduce himself, something that Kaigaku took notice of is a lack of surname he guessed the man was in a similar situation to himself.

“I'm Kaigaku, just a wanderer swordsman.” Kaigaku said, wanting to speed up the conversation he only decided to deliver this personally instead of just putting the money in the hand of this guy for information.

“I see you also don't have a family. Well, it happens with some frequency. But I owe you something so please name it and I will deliver to the best of my ability.” Gatou said much to Kaigaku happiness. It seems the guy is going to be straight forward.

“I'm investigating the murder of heads in this town. Can you give any information about his victims.” Kaigaku said with a serious tone of voice, the merchant was confused this was not what he expected to be the request.

“Well I heard rumours that everyone killed is part of a secret brothel in this village and that all the victims are part of there, but unfortunately you can only get the location of the place by another customer or one of the girls.” Gatou said, making Kaigaku think about his next action.

This made things difficult for him. This information didn't help. He will basically make everyone in this village except for the old women as probably knowing the location, and interrogating everyone will take time.

“I think this information is too little. Are you sure you don't want anything else?” Gatou said taking Kaigaku out of his thoughts, this annoyed Kaigaku he was expecting this man to just walk away after delivering the information.

“Yes, you have nothing that I can use so just leave me alone.” Kaigaku said walking away from the man, he now needs to think things with patience, a wrong movement and more people will die which will mean that he will be seen in a more negative light by the demon slayer corp.

“Hey mister, I think I can help you.” The voice of a kid took Kaigaku back to reality and he saw the kid that he helped walk in his direction.

“I heard that you want to participate in the brothel, I know someone that can give you the location.” The kid said, Kaigaku was confused about how the kid knew this information but he didn’t dwell too much into it, after all the kid apparently didn’t realised the money Kaigaku delivered was a low quantity or maybe the kid is just thankful with a low quantity.

“Oh? And who that person might be?” Kaigaku asked with an impatient tone, he doesn't trust this kid a single bit, everything about him screams untrustworthy, but Kaigaku is sure he can handle the problem.

After that the boy indicated for Kaigaku to go towards a man that wears a pink kimono, he set off immediately towards the location; there's no need for him to wait until later.

Upon encountering the man he waited until he was capable of talking with the man alone. “Stop here scum! I know about your brothel, so you better tell me where it is.” Kaigaku said, pushing the man into a wall and pointing his nichirin at the man's neck.

Kaigaku’s crow looking at the scene in the sky was already accustomed with this operation. It's harmless as he knows Kaigaku would never kill a human, although he beat a man for a while once.

“Ah okay okay I will tell.” The man said expecting Kaigaku to release him but Kaigaku was not moving until he heard the answer. “It's in the middle of the village in the udon restaurant, come when the moon reaches the top of the sky.”

“Good but I still need to know who is the last man that takes the dead girls.” Kaigaku said and the man was going to talk but Kaigaku cut him off. “And don't try to play dumb you know exactly what I'm talking about.”

“Okay okay, I don't know the guy's name but he's always the first to leave the place, he even threatened me to say nothing or he would kill me so please don't mention my name when you die.” The man said.

What he said annoyed Kaigaku so he punched the man in the gut. “Don't lump me with weaklings that die so easily.” Kaigaku said and walked away.

Everything was not good in Kaigaku's mind, things are never that easy. He's completely sure that this man is working with the demon and wants Kaigaku eliminated, nevertheless he will not back down.

Time skip to a montage of Kaigaku training his Techniques and reading an old book.

Night arrived and Kaigaku decided to go immediately to the location that he needed to go, he hid himself in the top of a house nearby just waiting.

When midnight arrived Kaigaku saw many men entering the place, he tried to discern who is a demon but at his distance noticing that would be difficult.

So he waited for an hour then for another hour, then another, when he was going to just enter the place and go search for himself the door opened and a man left the place with a woman.

He decided to wait for a few streets until he attacked, then he followed quietly and in a distance until he took notice of the man going to attack the girl.

He immediately jumped into action stopping the punch with his nichirin, but taking a close look into the demon face his calm way stopped.

He's fighting against one of the twelve kizuki, more precisely the lower two, the demon in question glared at Kaigaku and grinned upon realizing that he’s a demon slayer.

“Thunder breathing third form; Thunder Swarm.” Kaigaku said not even caring for the safety of the girl he just saved.

In this form Kaigaku started to spin around the demon while releasing countless slashes in a wavelike form. At the beginning the demon started to dodge some attacks but with each completed spin Kaigaku speed increased and so was his power, by the time Kaigaku returned to the starting point he delivered many slashes towards the demon and now the demon was going to be decapitated but he utilized his blood demon art, at the last moment right when Kaigaku reached the neck.

A piece of the ground suddenly went up and at an absurd speed gave Kaigaku a push, making him go a few feets away. “YOU BRAT, YOU SURPRISED ME THIS TIME BUT THIS WAS A LUCKY SHOT.” Lower Two shouted, regenerating the wounds, luckily for him they're all superficial because Kaigaku decided to play around thinking that he was going to finish with his last movement.

Balancing himself in the ground to not fall, Kaigaku barely dodged a stake of earth that followed his descent, grasping his nichirin with two hands Kaigaku darted in the direction of the demon.

But when he reached a range to swing his nichirin the ground started to smash him by all the sides, he jumped in order to dodge but he barely did this as his left foot took a bit of the pressure.

But he used this to put his foot in the cube that formed, gaining himself a boost and approaching the demon. “Thunder breathing Fifth Form; Heat lighting.”

Kaigaku knew that getting in slash range was a bad idea so he uses the technique that will allow him to deal an attack with more range, 5th form launched slashes that went down with him holding the nichirin at the utmost limit of the handle to increase range.

It was a success as Kaigaku attacked the demon's neck but it didn't penetrate the skin. At this moment Kaigaku saw that the demon protected himself covering his neck with his blood demon art.

“Damnit!” Kaigaku shouted and quickly tried to put distance but the cube from behind made a hand that slapped Kaigaku in one of the buildings nearby.

In the crash Kaigaku clearly coughed blood but he immediately stood up ready to continue the fight this time he went towards a rooftop, he really needs to evaluate the situation, his techniques are sloppy due to the lack of the first form, which makes impossible for him to go in and out of the enemy range with ease, and worst of all due to him underestimating the enemy at the beginning he received those injuries.

“Going up to avoid earth, it doesn't matter I will crush everything around!” The demon shouted but Kaigaku wasn't preoccupied with this.

Firstly he took notice that the larger the creation the slower the movement, and he doesn't care about the innocent lives that will be taken as long as he can survive and kill the demon.

The demon did as promised and large hands appeared and they started to destroy the surroundings, they're quick to a normal person or for some low ranking slayers.

But Kaigaku can easily dodge those, now the next action is a bet, he's expecting that the demon needs to solely focus on the hands and will not activate a quick earth attack.

He walked around towards the back of the demon and went towards the offensive. “Thunder Breathing: Secon-.” Kaigaku was forced to stop his attack as the demon merely raised his left foot and made a wall of earth that pushed Kaigaku away and in that moment they're changed to stab Kaigaku.

He falls to the ground and the demon looks at him. “Fool! While on the ground I can feel anyone's presence.” The demon said and then he noticed that many people were coming to see all the noise the battle created. “You will die soon, so let's eat. You made me waste too much energy.”

Kaigaku crow went in his direction shouting to see if he's still alive, this battle also made some other animals wake up, a bird, a rabbit, a tanuki all appeared surrounding Kaigaku, for some reason animals are fond of him.

“Now is not the time for animals to surround me.” Kaigaku muttered angrily, but the animals kept licking wounds.

Kaigaku is sure that he broke his ribs, and some bone in his left foot, and those last stabs it's only a matter of time before he dies of blood loss, okay maybe he’s exaggerating the wounds are not that deep.

But he's not going to just admit defeat so easily, he can still fight so he weakly stood up ready to continue the battle.

“Calm yourself young man.” Kaigaku heard the voice of a man talking behind him but he couldn't turn around, but the voice is calm and relaxing.

“Remember the words in that book you encountered in that abandoned temple, you still read every day.” The voice said and Kaigaku remembered of course he does, he read that book all the time but he can't understand most things it's trying to say.

“Open your five senses, understand everything inside your body, everything that makes your blood pump, for that you must relax.” The voice said and Kaigaku did as instructed trying to feel everything.

Thanks to the calm voice he's capable of easily calming himself even if he's hearing many cries of help from civilians.

The voice is weird but Kaigaku is thinking that due to the dangerous situation his head is just making him experience what he read in that old book into reality.

“Clear your mind and focus on what you need to do, ignore some of your senses, remember that after today using this is going to be difficult, currently you're in a high alert situation.” The voice said and Kaigaku felt himself getting lighter.

But he also took notice that he's seeing inside his own body not only that but the demon is also with only the muscles in sight.

But he didn't care about this; he only dashed in the direction of the demon. “Thunder Breathing: Fourth Form Distant Thunder.” Kaigaku delivered many slashing attacks multidirectional in the demon direction.

Due to being so weirdly out of tune with his body Kaigaku didn't hit the neck but he removed a leg and an arm of the demon, which isn’t absurd the move is mostly to create an opening rather than to eliminate.

The demon was in shock with this event. Not only was Kaigaku still trying to fight despite the injuries but he also couldn't sense Kaigaku movement. It was like someone without a will was moving, the demon doesn't base his sensing towards sound it's basically something filled with bloodlust.

Since the beginning Kaigaku was with low bloodlust at least for a demon slayer that normally hates demons but now he lacks any type of bloodlust, something that should be impossible in a fight.

Nevertheless the demon attacked using the earth trying to bring time to heal himself. It launched 10 big earth stones in Kaigaku’s location and he decided to jump away. “Five attacks.” That voice whispered towards him.

“Second Form: Rice Spirit.” Kaigaku shouted and delivered five successive blade strikes in semi circles around himself, breaking stones the launches in his direction.

“YOU DIE NOW!” Kaigaku shouted in the direction of the demon who healed his wounds at the time. Kaigaku is now excited with the fight, he wasn't one to care about battle but now he's feeling good.

Kaigaku darted in the direction of the demon, dodging some earth attacks that the demon launched. It seemed that for a flicker of a second the demon's eyes needed to look in the direction he wanted to attack, or he needed to move his arm or leg to attack. Two things that Kaigaku started to notice and predicting the attacks.

And Kaigaku now with this new world can dodge with ease. “Second Form: Rice Spirit.” He delivered five semi circles strikes, four removed the arms and the last went towards the neck but when it made contact with the earth protecting the neck it didn't budge, and Kaigaku could swear he heard a crack sound coming from his nichirin.

The demon quickly used the earth and created limbs of earth, but when he completed Kaigaku was already away, breathing heavily.

“You have many useless movements, wrong footwork, and the angle of your wrist.” The voice said, which annoyed Kaigaku.

“Well I'm trying my best! So shut up.” Kaigaku muttered and had to immediately dodge a stake that went in his direction.

“DIE ALREADY I AM LOWER TWO, I Can't Lose to WEAK DEMON SLAYER LIKE YOU!” The demon shouted much to Kaigaku annoyance.

“Distant Thunder.” Kaigaku used this while in the air to destroy some hands that followed him to the rooftop.

“Tch time to end this waste of space.” Kaigaku said but felt himself stumble a little, his vision is also starting to get blurred and he's losing the boost in speed and the transparent vision.

Kaigaku jumped from the rooftop and directly towards the demon but in mid air he heard something. “You won't kill him with this move, and I'm not insulting you, just once I can help you and I will show you how to perform movement without waste.” The voice said and in this moment Kaigaku is sure that this isn't just his mind playing tricks.

He would never guess that ghosts are real, but reluctantly he lets the ghost control his body, for him it doesn't matter how he wins, only that he survives. For a split second he could see a red haori.

At this moment he started to see his body from an outside perspective and many earth stakes appeared surrounding his body.

“Sixth Form: Rumble and Flash.” His body said and in this moment in the blink of an eye he delivered many thrust attacks that destroyed all of the stakes in his direction.

He closed the gap of distance. “2nd form Rice spirit.” In the blink of an eye the five blade strikes went destroying the earth limbs of the demon and in the end went towards the head removing with ease, and Kaigaku heard another crack sound coming from his nichirin.

Kaigaku seeing his body do this was amazed he never expected to see his body do such clean moments. It felt like thunder was truly being imbued in the attack, it was so much better than what the rotten old man showed him, and also breathtaking.

“Why! I did so many things correctly, why!” The demon shouted lamenting the events. He remembered in this moment his life as a human, he was a problem child from an early life screaming about most things that happened.

He was scared and lazy he always wanted to have the attention of girls growing up he became someone that went in places that offered services.

He never did anything other than scream and go towards women, but he wanted to be brave as little kid he always dreamed of the samurai, he wanted to become one.

But so many people shut down his ideas that he started to see himself as worthless, he was brave once but lost that in the end he just became what the others told him to become.

But that didn't matter. The demon is gritting his teeth with anger. “Attack him now!” The demon shouted before dying and a tiny figure dashed towards the body of Kaigaku.

The nichirin blade was immediately put into the neck of the attacker, who stopped revealing to be the kid that Kaigaku saved earlier.

In this moment Kaigaku recovered control of his body and he started to see things normally once again. “So I was correct, too suspicious how a kid would know so much information, you better step back or I will kill you.” Kaigaku said in an angry tone that made the kid back away.

Not many seconds after he stumbled his vision was certainly getting worse. “Damn, wonder if that merchant would still like to help me.” Kaigaku said and before he got the chance to run his crow interrupted him.

“Kaw kaw, Kaigaku go towards mount Natagumo soon, go soon!!” The crow said and Kaigaku gave out a tired sigh.

He then started to run towards the edge of the village, the only location where there’s a place that will take care of horses.

Arriving at the place he was surprised to encounter the merchant awake and taking care of a few horses. “I was waiting for you demon slayer.” Gatou the merchant said, hearing the steps of Kaigaku.

“You knew… that explains your insistence. I need help getting towards Mount Natagumo.” Kaigaku said and Gatou nodded his head but was not happy with this idea.

“Why don't I get you treated first?” Gatou said but only received a glare from Kaigaku. “Sure then just follow me, I was planning on leaving this place as soon as possible.”

Kaigaku nodded his head and took a step forward but in that moment he lost consciousness falling face planted in the ground, with Gatou screaming and going to help Kaigaku.

Chapter Text

Kaigaku never saw his parents, he has no idea how they look like from what he heard his father died from a illness he got bad luck and was too prideful to do something bad in order to survive resulting in his death.

His mother died at childbirth and with her last breath she gave Kaigaku his name and died with a smile on her face, Kaigaku was raised by a friend of his mother that owned her a dept.

But after Kaigaku turned six she expulsed the boy saying that her debt was payed and that he was on his own from that point onwards.

He remembered doing everything do survive, he was a kid so he went around stealing money or food from others but the result was sometimes terrible.

“You little runt! Get away from here now!” A man yelled kicking Kaigaku in the head, the boy is weak he was eating poorly.

The man that kicked him was someone that Kaigaku tried to steal food from but it failed like it did most of the time.

Kaigaku run from the man but when he goes to a far distance he show a bread that he successfully took. “Idiot, should pay more attention in your surroundings.”

That was how he went most of the time never once was the boy shown the good of others, people merely shunned him and went around killing him.

Those that talked and helped him are only criminals they gave Kaigaku hints how to survive, where to go in order to have a bed, all of those events led to Kaigaku not caring about anything other than his survival, he even drunk water from the rain all tarnished from being on the dirt ground as to survive of dehydration.

He only saw people attacking each other so he decided to become like them, but once he saw a different side of humans, a side that he considers abnormal.

“You die now brat!” A woman yelled while she's punching a eight years old Kaigaku that's on the ground curled up.

He barely felt pain he was accustomed to it, she won't kill him he's sure if it, he thinks that people like to have a punching bag someone to vent frustrations, even though that's not the truth people are just not bad enough to kill a child, but Kaigaku thinks that anyone on the town can kill him without remorse.

But suddenly felt the the strikes stopping, confused he opened his eyes encountering a tall man, with some kids surrounding him.

The man said something but Kaigaku didn't hear as in this moment he woke up from his nightmare, his face is one of fear, but he looks around frantically expecting to see something of danger but he realised he's inside of a wagon.

He relax remembering that he asked that merchant for help, looking down at his body he noticed that he's with some bandages around his body.

“Hey you, you're finally awake.” A female voice said, making Kaigaku quickly look behind him, encountering a girl probably the same age as himself, she has short black hair with bright blue eyes.

“Who are you?” Kaigaku said harshly trying to stand up but failing as the wagon is still in the move, he was going to fall but the girl caught him before he could.

“I'm Haku, daughter of Gatou.” She said making Kaigaku sit in the bench once again, looking up Kaigaku encountered the sun striking strong in the sky, he frowned at the view.

“How long was I out cold.” Kaigaku asked looking at Gatou in the front of the wagon where Gatou is commanding the horse.

“Difficult to tell, but my best guess is going to be eight to ten hours.” Gatou said, Kaigaku sighed and looked down at his hands. “I am guessing you wanted to sleep less by your reaction.”

“Yes, I only sleep four hours, more time sleeping means more hours without training.” Kaigaku said angry but he calmed down he should only be angry at himself for this mistake. “Are you going to mount Natagumo as I instructed?”

“Yes, we will arrive at night there.” Gatou said, with Kaigaku nodding his head.

“Hey don't ignore me!” A feminine voice said, poking Kaigaku stomach he grunted glaring at the girl.

“I have more important business to attend.” Kaigaku said angry, he then looked around and decided to ask the girl this time. “Where's my crow.”

“What crow? I have been awake only a few minutes before you.” Haku said, making Kaigaku even more angry the girl don't want to be ignored but knows both about the information he needs.

“He's here, the creature didn't leave your side for even a second only when he saw you waking up he decided to sleep.” Gatou said, this information made Kaigaku calm down.

“Yeah and weirdly a lot of birds always appeared to peck at you, it's weird why would sweet animals like a brute.” Haku said but Kaigaku only sighed laying down in the wagon once again.

“Maybe a spirit guide me.” Kaigaku said in a joke tone but with the events of the previous night he think this might be true.

Kaigaku took book that was tucked inside his corp uniform and started to read, it's a old book probably from the Sengoku period, a miracle that it's still intact with only a few marks of age.

“Hey! You can't just start reading a book and ignore my beautiful self!” Haku yelled but Kaigaku ignored her, he have no obligation to indulge in any type of dialogue.

He only needs to arrive at his destination and never talk with them again, and it's even more important for him to read the book that seemingly holds a ghost inside of it.

He will revise the part where the ghost was teaching him about, he remembered reading that it was like an ascended state he ignored that part founding to be too fake to be true.

But with the events of last night he will have to read more about that part this will be his focus from this point forward, knowing how to access that state twenty four seven.

It shouldn't be that difficult considering he can maintain total concentration breathing at all times, but this will certainly be a good challenge for him.

“HEY don't ignore me!” Haku shouted, and Kaigaku was ready to knock her out but Gatou took notice of this action.

“Stop pestering Kaigaku, Haku! He needs to rest for his next mission, and considering they didn't let him recover his wounds it's probably important.” Gatou said with a hint of fear on his voice, the girl reluctantly decided to let Kaigaku alone.

After that the trip went smoothly without anyone interrupting Kaigaku, and he got a good grasp into the access to the other plane whoever wrote this book is a excellent teacher while at first it sounds too fictional once you have a minimal understanding it came as easy.

But Kaigaku still couldn't use not even once while in the Wagon, but night arrived and the mount came into view with Kaigaku leaving the wagon.

But before he could walk away Gatou decided to talk with him about something. “You should open up Kaigaku.” Gatou said, taking Kaigaku by surprise this wasn't what he expected to hear.

“And who says I am not?”

“You're orphan I presume since you never told me your last name.” For this Kaigaku only kept observing Gatou. “I was in a similar situation, I understand having no family but other people can still be your friends they can become your family, you let people go away because you think something is lacking, like you never get satisfied.”

Kaigaku frowned at what the man said it was clear he failed to see the bigger picture, Kaigaku doesn't care about his family, and never being satisfied of course he's satisfied… or is he, it doesn't matter Kaigaku wasn't going to listen this old guy advice. “Where are you going with this?”

“I never saw you smile even once Kaigaku, I have a feeling that your happiness is temporary. So try and connect with someone or even try and discover why you're not happy.”

Kaigaku had enough of this nonsense so he just run in the direction of mount Natagumo, going to carry out his mission nothing else truly matters at the moment.

Walking in the mount he encountered many corpses of fallen demon slayer corps but the weird thing is that they all have slash wounds, but Kaigaku only kept going forward.

It's clear by the scenario that things are serious and a powerful demon is nearby which made Kaigaku instinct flare up. “Twelve Kizuki.” Kaigaku heard the same voice from the other night whisper to him.

But this didn't made Kaigaku falter he continued moving forward. “It's fine, they wouldn't send someone below hashira to fight the top three upper moon.” Kaigaku said, in a way to reassure himself.

He then moved forward, taking glance of a big buffed demon fighting someone with a boar mask but he ignored feeling something more dangerous inside the forest.

He didn't stumble upon Zenitsu which was unfortunate as it would give him a good laugh due to the state Zenitsu was at the moment.

But he kept moving forward and he encountered, a boy decapitating a demon but Kaigaku was capable of seeing a glimpse of the demon's eye.

“Tch I wasn't even needed, that's what I get for talking with some random.” Kaigaku muttered to himself, he observed the boy crawling but what took his attention was the demon's body standing.

“Removing your own head? That's new.” Kaigaku thought to himself waiting for the moment where the demon would reconnect his severed head.

When he did that he didn't even hesitated and went straight towards the demon. “Thunder Breathing Fifth Form: Heat Lightning!” With a thrust with his nichirin blade Kaigaku after the long thrust delivered a slash decapitating the demon.

Kaigaku saw the demon body trying to go craw towards the boy who by that point was hugging someone while on the ground.

Kaigaku thought about cutting the body to many pieces but the weak demon doesn't deserve to receive more damage from his nichirin.

But he walked in the direction of the boy seeing him putting a hand in the demon back he put his foot into the demon clothes.

“You idiot, don't take pity from someone that murdered humans, I get it he looks like a child but that means nothing he probably lived for hundred of years.” Kaigaku said, with scowl on his face.

The boy started to go on a talk about how demons where once humans but Kaigaku wasn't paying attention because first he was curious why the boy is holding a demon, and second Kaigaku would do the same thing to a human so what the boy is saying means absolutely nothing to him.

“Hey why do you have a demon with you?” Kaigaku asked, pointing at the girl.

Okay I was going to call him the boy and Nezuko the girl but I'm annoyed with that so I will just call them by their names.

Tanjiro answered immediately. “That’s my little sister! And I.”

Kaigaku was baffled at this response. “That's dangerous you know, and how many people did she kill at the moment?” Kaigaku said, his face continued with a scowl but he did not a single sign of attack.

“She's not dangerous! And she stayed without eating a single person for years!” Tanjiro shouted, Kaigaku hummed at the boy response.

But he decided to sheath his nichirin. “Okay you got my attention! Lucky for you I have nothing against demons.” Kaigaku said crouching to be eye to eye with Tanjiro. “I am Kaigaku, what's your name?”

Tanjiro was stunned for a few seconds he wasn't expecting this guy who a few seconds ago killed lower five with a sneak attack, and immediately talked bad about Tanjiro showing kindness to the dead to act this way.

In truth Kaigaku only kill demons that he receives orders, different from many he never lost his family to a demon there was a case with a demon before but Kaigaku is still alive after that so he has no need to hate demons for that.

In fact that single thing made Kaigaku realise that demons and humans are the same which is not surprising considering they were once humans, so Kaigaku view the demon the same way he view humans if for some reason he turned into a demon he would easily kill humans for his survival, because humans never gave him a reason to like them.

“I'm Tanjiro Kamado! Thanks for your trust.” Tanjiro said, with Kaigaku went to help him get up but right when Tanjiro was going to take Kaigaku hand a person appeared besides the three.

Gyuu Tomioka appeared looking around he saw the clothes in the ground. “You two killed the kizuki.” He stated, looking at the boys but his eyes remained on both Tanjiro and Nezuko. “You..!”

In this moment Tomioka noticed something and blocked an attack with Shinobu appearing taunting Tomioka. “Now move, Tomioka.” Shinobu said pointing her nichirin to Tomioka.

Kaigaku was confused with the shape of the nichirin it didn't seem capable of beheading a demon but Kaigaku dismissed this thought, no one would accept a demon slayer incapable of decapitating a demon.

“”Why did you say that everyone hates me?” Tomioka asked taking everyone by surprise.

“Oh dear I guess you never realized that people hated you sorry. I shouldn't have said anything my apologies.” She said and decided to talk with Tanjiro.

Kaigaku by this point was clearly just waiting for Shinobu to strikes he knows that most demon slayers hate demons so talking with them would be crazy unless someone was helping them which he suppose is what Tomioka will do.

“Boy! You're lying on top of a demon. That's dangerous so get out of the way and…”

“No! You've got it all wrong! Well not the wrong but… umm… she's my little sister and…”

“Oh! Is that so? How sad in that case… I'll use gentle poison to kill her so she won't suffer.” Shinobu said, making Kaigaku annoyed she seemed to be mocking Tanjiro like it reminded him of some words that he heard as a kid.

“Can you move?” Tomioka asked, with Kaigaku quickly catching up on the conversation.

“Don't worry I will carry the two, can't let them die here.” Kaigaku said, without even having time to think he said on instinct so unlike himself he will probably die if he gets caught but he is curious about this boy and girl and most important he's annoyed with the tone of voice from that girl, it's really simple he's not doing this for a selfless reason.

Without Tanjiro even having time to process Kaigaku takes Tanjiro and Nezuko carrying them like a sack of potato, then he run away from the two hashira.

“Why are you doing this?” Tanjiro asked, Kaigaku frowned he wasn't in the mood to talk at the moment.

“I felt pity, but you should be thinking about the consequences of our action.” Kaigaku said, as he almost tripped due to his left foot still being injured.

Tanjiro stopped talking as he clearly noticed that Kaigaku isn't in full healthy conditions, but he was more worried that he might make Kaigaku stop being a demon slayer due to him.

But Kaigaku immediately jumped from an attack delivered by a demon slayer, Kaigaku glanced at the girl and went to run away but due to a wrong move of his foot the girl caught up and delivered another attack.

Kaigaku dodged but he got angry. “They won't kill you.” Kaigaku said, confusing everyone but in the next second he throws Tanjiro at a nearby tree, being successful in making his right hand free.

The girl went for another attack that Kaigaku blocked with his own nichirin. “You die Now!” Kaigaku shouted with a angry expression on his face, no one attack him and will live to tell the tale, if she thinks he's worthless he will destroy her.

He went in the offensive but carrying a demon, plus some injuries will definitely make him not attack at his top performance, so he went for a slash at the girl leg with but he only grazed her.

The next moment she went for another attack which he easily blocked but the result is his sword breaking in half, but he quickly kicked the girl to put her at a distance.

He expected this to happen, lower two clearly did some heavy damage in his nichirin but honestly he was expecting a few weeks until it broke.

“Thunder Breathing Second Form: Rice Spirit.” Kaigaku was going to use this technique but right when he was going to remove one of Kanao arms something made him stop in his tracks.

“Message! Message! Kaww! Take Kaigaku, Tanjiro, and Nezuko into custody… And bring them back to headquarters, capture Tanjiro and the demon Nezuko! Then escort Kaigaku to headquarters.” A crow shouted making Kaigaku scowl, he isn't bothered by the wording it's clear they called him for a different reason than Tanjiro.

“Isn't this your lucky day.” Kaigaku said sheathing his sword, he really wanted the message to wait for another minute or even ten seconds it was all the time he needed.

Chapter Text

Kaigaku wasn't expecting to encounter the Hashira but that's of no consequence, although he wonders where they took Nezuko, at the moment they're just waiting for Tanjiro to wake up, the boy in question is restrained on the ground unconscious, Kaigaku was only kept without restraints due to his cooperation after the message, but his nichirin is not with him mostly because he tossed away after the battle.

But he was certainly surprised after encountering Giyomei Himejima. He heard that a man was arrested and a girl survived the morning after that incident, but he didn't know the details.

But that's fine, Giyomei is blind so Kaigaku only needs to deny knowing the man, just a coincidence to have the same name it's simple.

But returning to the current problem Tanjiro has just woken up, and the Hashira started to talk how they should just kill the two at once, this made Kaigaku not happy in fact any type of view of the Hashira as honourable started to fade away on his mind, making him wonder how his master could be among those individuals.

“Forget about them. What are we going to do about Tomioka?” Obanai said, making both Tanjiro and Kaigaku look in his direction, but this action made Kaigaku remember that one of the hashira isn't crazy.

The Hashira started to question Tanjiro but Kaigaku wasn't paying attention to any of this nonsense. He knows someone else is the leader, he doesn't care about those Hashira, with a scowl on his face he ignores everything around him until something catches his interest.

“Awww he's possessed by a demon. Hurry up and kill this child to set him free.” Giyomei said that which immediately made Kaigaku angry but he did nothing in response he's outnumbered, sometimes Kaigaku wondered if he was incorrect in putting his life above those in the temple.

He wondered if those in the temple were worth saving but this phrase made Kaigaku regret not encountering a stronger demon that would finish the job, safe to say anything that those Hashira tell him he won't follow they aren't his comrades they're co workers at best.

What caught his attention once again was Sanami appearing with Nezuko box. The next thing he did was to cut Nezuko inside the box, Kaigaku was going to ignore it but he then saw Tanjiro getting in position to attack.

So if he's going to die he will die with resistance, so he followed Tanjiro and also went for a strike. “Stop, the master will be here soon!” Tomioka shouted, but the action continued.

Tanjiro dodged a strike of Sanemi while doing a headbutt meanwhile Kaigaku kicked Sanemi on his knees, the result was Sanemi on the ground, Tanjiro kneeling with Nezuko box behind him, and Kaigaku returned to his position acting like he did nothing.

“The master of the mansion has arrived!” A kid shouted and a man that looks like a corpse entered.

“Welcome my dear demon slayers.” He said and upon looking onto his face Kaigaku felt like he discovered something completely new like someone lied to him.

“Good morning everyone. It feels like a beautiful day. The sky is a perfect blue isn't it? It makes me very happy that we can have our twice-yearly hashira meeting…. Without any members having changed.” The leader said.

Kaigaku is speechless. The man clearly needs help even to stand up if the two girls holding his hand is an indication he remembered his master telling him about the demon slayer leader being an honourable man but Kaigaku remembered that not even once he heard about the man's strength.

For Kaigaku this must be a sick joke, while the demons have from what Kaigaku heard the strongest demon as their leader, the demon slayers have their weakest member as the leader.

And by how terrible the demon slayer test is, he finally understands the reason because he's sure that the previous leaders were weak as they're all family. Kaigaku remembers some people that clearly had potential being eliminated by that big demon or even by some type of surprise attack.

Kaigaku was smart to pick his battle but he almost got caught by that big green demon and death was guaranteed he's sure of it, for Kaigaku the strongest should be their leader if the strongest was the leader Kaigaku is sure that the amount of corpses he saw in mount Natagumo wouldn't happen, because a strong leader would not send novices to fight a kizuki.

Kaigaku saw everyone bowing even Sanemi forcing Tanjiro to bow, Kaigaku wasn't going to bow specially to a blind man that probably can't even tell the difference, but he remembered that his life is probably in the line so he decided to kneel by Tanjiro right side.

“Master, I sincerely pray for your increased happiness. It is good to see you healthy.”

“Thank you Sanemi.”

“I'm sorry, but… Before the hashira meeting, would be so kind to tell us… about this corp member who travels with a demon, Tanjiro Kamado?”

“Yes, my apologies for surprising you. I have accepted Tanjiro and Nezuko. And I want everyone else to do the same.”

Kaigaku was quite surprised by this announcement judging from the Hashira he was expecting the leader to act the same way, maybe he misjudged the leader.

But the hashira continued to act like idiots not accepting the judgement which made Kaigaku even more annoyed.

“Well then. The letter.” Ubuyashiki said, in sequence one of the kids started to read the letter saying how a former hashira is vouching for their acceptance, with Tanjiro, Urokodaki, and Tomioka will commit seppuku of Nezuko ever eat someone.

Kaigaku didn't seem to be affected by it, I mean it's clear that death was already a possibility so this promise seems to be more delaying the inevitable.

“So what if he'll commit seppuku?! If he wants to die he can rot! It doesn't prove a thing!” Sanemi said, with Rengoku answering with something similar, Kaigaku for the first time agrees with the Hashira their promises are very pointless and stupid having one less hashira due to something out of his control is stupid.

“That's correct I cannot guarantee or confirm that she will not attack people. However you cannot prove that she will attack people. It's a fact that Nezuko has not bitten anyone for over two years. And four people have staked their lives on her.” Ubuyashiki said.

And Kaigaku took notice of the number four there was clearly someone that shouldn't be counted and he suspected it was himself, which is fair considering he almost killed another demon slayer.

“If you would reject this then you must offer something greater than Urokodaki’s promise. Furthermore Tanjiro has crossed paths with Kibutsuji.”

The hashira entered in mayhem but Kaigaku wasn't that impressed it's clear that Tanjiro didn't fought the man or he would be dead, probably a simple sight and he was gone but Kaigaku is certainly questioning why Tanjiro would be kept alive.

Okay let's skip ahead everything happened the same, Sanemi brought Nezuko to a shade he made himself bleed, she rejected the blood, Kaigaku was just seeing how pathetic the hashira looked seeing then as children throwing a tantrum.

“That's enough talk on this subject. Tanjiro you may leave. It is time for Kaigaku promotion and the hashira council to begin.” Ubuyashiki said, with Tanjiro taking a while to leave but when he eventually left everyone took a close look at Kaigaku who scoffed, he will make sure to not respect the others hashira.

“Well, it has come to my attention that you Kaigaku killed lower moon 2 alone, and you saved Tanjiro Kamado against lower moon 5.” Ubuyashiki said, Kaigaku nodded his head but the other hashira didn't seem impressed by this information.

“While you protected a demon and almost killed a fellow demon slayer, the demon in question is now at our side and you didn't killed another demon slayer so nothing will happen to you.”

Hearing this made Kaigaku sigh with relief but he noticed that Shinobu was not pleased by this, Kaigaku made the connection that they probably know eachother due to their similar hairpin, to that he smirked.

“Got a problem with this insect girl?” Kaigaku said in a provocative manner, Kaigaku knows he shouldn't be doing this but he's still angered that the girl would attack another demon slayer without a provocation.

“Not at all, it's what the master decides.” She replied with a smile on her face that made Kaigaku unhappy he was expecting another reaction.

“Well then I hereby declare Kaigaku as the current Rumble Hashira.” Ubuyashiki said, I didn't mention before but Kaigaku was rank Kinoto going towards Kinoe.

Kaigaku is happy with this news it clearly shows who is the superior between him and Zenitsu, showing how wrong the old man was by putting the two in the same level, Kaigaku is superior to that failure.

Well I don't know what happened in the Hashira council so I will just skip it.

After that Kaigaku was advised to reside in the butterfly mansion while his wounds are treated and his nichirin is reforged.

He will get a isolated room but he wanted to talk with Tanjiro so he was guided there, upon entering the room the first thing he took notice was Zenitsu but just as quick as his eyes noticed him it also left going in Tanjiro direction.

“Kaigaku.” Zenitsu muttered, but it went unnoticed as Kaigaku continued to walk towards Tanjiro.

“Kaigaku-san! I hope you didn't get in trouble because of me.” Tanjiro said, as Kaigaku sit on Tanjiro bed.

“Nothing to worry, I was actually promoted to hashira level.” Kaigaku said, hearing a gasp from Zenitsu.

“Oh that's great! So you're going for a mission soon.”

“I wish but I have to heal my wounds and I will need a new blade, so until then I will also be in the butterfly manor.”

Tanjiro however noticed that from the moment Kaigaku entered the room Zenitsu has been staring him and was also extremely surprised when Kaigaku talked with Tanjiro.

“Kaigaku-san do you know Zenitsu?”

Kaigaku scoffed and looked away thinking how he should answer this. “Yes I know that wimp we trained under the same man, anyway I am leaving, come to my room when you're good enough to train.” Kaigaku said, leaving the room not letting time for Tanjiro to go in Zenitsu defence.

After that Kaigaku took a wooden sword and decided to practice his breathing forms, he even tried to use the first form but as always he failed.

This continued for a few days as Kaigaku trained most of his time, trying to mimick when his body was possessed or even to see that strange vision but the movements improved he didn't made progress with the vision.

But on a unexpected night he encountered a unexpected visit.

He was getting ready for his four hours sleep when something entered the window of his room, noticing this he immediately went in a fighting position, but relaxed after seeing the person.

“It's only you Tanjiro sister… What was your name?” Kaigaku said, but Nezuko only tilted her head to the side. “Right you can't speak, something about hypnosis.” Kaigaku stayed in silence staring at the girl for a few seconds until he remembered something.

“Nezuko! That's your name. But I still don't know what you want.”

Nezuko merely took a sit in his bed, making Kaigaku sigh he wanted to sleep but clearly this isn't going to be possible. So he sits besides her.

The room after that was in a silence that Kaigaku could hear her breathing but with how she can't speak he was starting to get impatient.

So he decided to carry her back towards Tanjiro room, but when he started to stand up she put one of her hands on his head, he was taken back by this so he looked at her face.

She seemed to be smiling but it was hard to tell, he wondered if she was thanking him due to the fact he protected her from Kanao but again he doesn't know.

Her next action however took him by surprise, she suddenly grow in size and pulled him into a hug, he stood still for a long time not knowing what he should do.

But eventually he reciprocated the hug, the reason for this action is because he saw the same ghost that helped him against lower moon 2, and it was clear that he wanted Kaigaku to accept what was happening so he did, not because he wanted but because he wants to know more about the ghost… or that's what he's telling himself.

But in the hug he wondered if with her demon senses she could tell, that he's tired or maybe she could tell that he's…

It doesn't matter but what's important is that he ended up falling asleep in Nezuko arms.

Chapter Text

After being protected by that tall man Kaigaku was taken in by that same man, living now in a temple. He quickly discovered that the man is blind.

Living at the temple was easy at the beginning but Kaigaku's mistrust started to pick up, it wasn't even such a difficult situation as most of the other kids had bad personalities.

He saw them lying to Giyomei the caretaker every so often, it wasn't anything serious but for Kaigaku who only saw the worst it was a quick reminder that he wasn't safe in this place, it was only a matter of time before they got tired of the extra mouth.

So he prepared his run strategy. He wasn't going to stay in this nest of snakes for a long time, but he grew accustomed to this living condition, having no need to drink muddy water or not knowing if he will survive another day.

Time passed and Kaigaku was still in doubt how to escape but he was irritated after one of the kids started to cry after she got beaten by Kaigaku in a game, in the end he was seen as the one in the wrong, being serious in the game.

As a comeback, Kaigaku decided to steal the money from the temple. He was sorry for Giyomei but those brats deserve to know that they shouldn't cross Kaigaku.

He was caught by the other children and basically expelled from the temple, his anger only increased as he knew that they would lie about him to Giyomei, he could only desire the worst to happen for them all.

But he encountered a demon he was with fear as the demon said that he would kill Kaigaku.

“Wait… i-if you spare me I can show you a temple nearby it's full of h-humans.” Kaigaku said, shaking with fear and even bowing to the demon.

There was nothing else he could do , he was merely remembered of the reality of this world and that he only exists to suffer he can only give insults for the gods that forsake him.

But the demon by Kaigaku surprises agreed and so Kaigaku led the demon to the temple and removed the wisteria incense and when the demon entered the temple Kaigaku ran praying for his life.

It was in that instance that Kaigaku realised that in this world only the strong survive, with this in mind he swore to get stronger and never again suffer by the hands of those cruel humans and demons.

With those last thoughts a figure with red haori appeared in Kaigaku dream, having seen all of the events the figure was saddened by this, specifically how unlucky Kaigaku seems to be as a child.

The figure wanted to say something to Kaigaku but decided to stay hidden, his communication is limited so he shouldn't waste it with sentimental things, he unfortunately needs to focus on Kaigaku training, but he wonders if Kaigaku is a good person to teach but Kaigaku was the one who picked up the book so there's no alternative.

With this Kaigaku woke up, looking around himself he was quick to notice that he's still in a hug with Tanjiro’s sister he was rather calm at this, since he remembered the events of last night clearly.

But in an involuntary move he ended up hugging her more firmly, he only continued to stare ahead knowing that it's because he's having that dream once again.

But he probably needs to stand up. Nothing will come if he doesn't train today, he needs to but there's no strength in his mind to move, the dream together with last night plus the warmth of the hug make the situation difficult to escape.

So he stayed there for a few more minutes. It's nice staying in such a position but he remembers something.

He asked Tanjiro to see him the moment he was capable of training which means he could appear at any moment, and it will be difficult to explain this situation.

But this brings the next problem: it's impossible for Nezuko to leave his room in the morning as avoiding all the windows would be impossible.

In the end he can only hope that Tanjiro won't appear but if he does appear it would be for Kaigaku's best interest to not be in this position.

As such he quickly got away from her, he was so fast and uncaring that he was surprised that she kept sleeping but he was quick to make her comfortable on the bed putting some sheets over her.

Looking at her face Kaigaku was unimpressed, so he merely decided to walk away from the room and lock the door, he's certain it's the best way and then when night arrives he will just put her inside the box.

Although going to his daily training, he wondered if she will continue sleeping this night it will certainly make putting her back difficult.

It wasn't long until night arrived and Kaigaku returned to his room, opening the door he was met with Nezuko still sleeping on his bed.

For a second he almost forgot what he wanted to do but, with Nezuko standing on his way to just fall on the bed it was rather clear what he should do.

He wasn't at all careful and merely picked her up like a sack of potato and carried her to the location of her box.

Arriving there he carefully put her inside the box, putting her inside he stared at her for a while. “Heh… You're lucky, having so many people that are risking their life for you, I have no one like that…”

With those last words he closed the box and went back to his room, sleeping as usual.

The next day, Kaigaku went to his daily training as usual but close to the end of the day, he was met by Tanjiro who looked tired for some reason.

“What happened to you?” Kaigaku asked, curious with what could possibly have happened to him.

“It's the rehabilitation training, it's rather intense…” Tanjiro said, with a dejected face Kaigaku continued confused.

“It shouldn't be that hard, it's only the support team against you, they're weak… but I guess you're still injured to beat them.” Kaigaku said, but he took notice of Tanjiro breathing and suddenly everything made sense.

Tanjiro was going to retort with something, probably trying to defend the girls but Kaigaku interrupted him.

“Hey Tanjiro do you keep total concentration breathing, active all the time?” Kaigaku asked, already knowing the answer but just incase he was just relaxing after the rehabilitation.

“...No I don't. Even while sleeping? Is that possible?!” Tanjiro said, and Kaigaku sighed it seems that what's obvious to him isn't to others.

Kaigaku from the moment he was taught the breathing techniques always tried to keep active all the time, he mostly did that because he thought it would be very inconvenient if he fought a long battle against a demon and he lost the stamina battle.

It was only after he passed the demon slayer test that his master explained that what Kaigaku was doing is something essential, Kaigaku at the time thought his master didn't mention it because it was common sense to try and increase the time of breathing, but now he's thinking this should be in the basic training probably many demon slayers would survive.

“Yeah you can… Well I was going to spar with you but I guess I can teach you this, but don't think it will be easy, because we will be fighting and keeping total concentration breathing. Prepare Tanjiro because if you're not in the rehabilitation training you we will be sparring!”

“Yes sir!” Tanjiro shouted, but he was slightly afraid with what he will be taught here.

With the passing days the two continued training and as the days passed Tanjiro informed that he could beat anyone except for Kanao which Kaigaku laughed remembering how easily he overpowered her but at least it gave Kaigaku an Idea about Tanjiro power.

Tanjiro also informed how Inosuke and Zenitsu stopped appearing in the rehabilitation which Kaigaku used as an excuse for Tanjiro to also stop coming.

He succeeded and in turn instead of going to the rehabilitation Tanjiro trains with Kaigaku, Tanjiro also tried to persuade Kaigaku to train the other two.

But he quickly turned down saying how he wouldn't train those that give up quickly, in truth Kaigaku doesn't like to help others get strong he's only training Tanjiro due to Nezuko and Kaigaku having almost died because of it.

With time Tanjiro was strong enough that Kaigaku said to him return to rehabilitation, the result was Tanjiro winning against Kanao, Kaigaku was present in the scene and was satisfied in knowing that the insect Hashira isn't capable of good training.

Kaigaku avoided Tanjiro after that event, as he didn't saw any reason to interact with him again, sometimes Tanjiro spared with him from time to time but Kaigaku always humiliated Tanjiro but it helped Tanjiro to increase his reflexes.

Zenitsu took glimpse of those from time to time and Kaigaku noticed but considering Zenitsu never went to talk with him, he saw no problem.

But that changed in a moment when Zenitsu approached Kaigaku when he was alone, Kaigaku said nothing and continued practicing his breathing techniques.

“Congratulations Kaigaku, it was -” Zenitsu was saying but Kaigaku interrupted him with a scowl.

“As expected, anyone with a functional brain could tell, except for the old man.” Kaigaku said, his face was clearly with anger, it's nauseating to be in the presence of someone like Zenitsu.

Zenitsu didn't say anything back, but Kaigaku wanted to make Zenitsu see how far is the distance between the two, he will thank Tanjiro later for giving him this information.

“I heard that you fancy Tanjiro sister?” Kaigaku said, his voice low with danger. Zenitsu looked at him confused.

“Nezuko-chan? What about her?” Zenitsu asked slowly, he knows whenever Kaigaku talk about something it's serious.

“She has been visiting my room every night, Tanjiro even knows, of course we only talk for a hour since Tanjiro wasn't the happiest.” Kaigaku lied through his teeth, after that single night Nezuko didn't try enter his room.

But he got an reaction from Zenitsu just as he expected, the yellow haired boy wasn't happy looking down. “I see, if-”

“Stop being a embarrassment, do something useful.” With those last words Kaigaku left, he have no need to continue seeing scum.

Next day it was finally time for Kaigaku’s new blade to arrive, he was happy to finally get his blade it means that he will get a mission, something that he's anticipating for a while.

It was the mid of the day with Kaigaku in his training session when a voice disrupted him. “It seems that you continue to work hard Kaigaku.”

Looking at the voice Kaigaku smiled. “Muramasa-san, it's good to see you. My nichirin sword is finally reforged I presume.”

“Yes, here take a look.” Muramasa said, throwing the nichirin to Kaigaku who caught without effort.

Removing the blade from the sheath, Kaigaku did some slashes and even performed all the five thunder breathing forms he knew.

“Good, the grip is perfect. As always you made a masterpiece Muramasa-san.” Kaigaku said, sheathing the sword.

“Now you always praise me Kaigaku, but if I ever create a masterpiece it won't break, this is your third sword but let's see maybe this will be the one.”

After that it went a silent for a while it was rather pleasant with the two looking at the clouds. “Let me show you how much I improved, Muramasa-san.”

With this Kaigaku continued training, with Muramasa watching him train.

At night Kaigaku was surprised by encountering Nezuko already on his room sitting in his bed it was a annoying sight.

He debated what he should do as such his immediate reaction was to walk away from the room.

But Nezuko quickly followed him, which made him accelerate his pace but she matched his pace.

He then started to just run, arriving outside the butterfly mansion. “What's up with her! Leave me alone.” Kaigaku muttered to himself, he's going to have a mission the next day so he wanted to sleep immediately.

Feeling a pressure on his back he falls onto the ground, in the ground he feels even more of a weight on his back so he carefully turns around.

Seeing Nezuko's face. “Really a tackle… damnit.”

Her face was very innocent so Kaigaku immediately thought that she wasn't really seeing him, from what Tanjiro told him she views humans as her family.

Due to her tackling she probably is viewing him as her brother. “Sorry but I have business.” Kaigaku said, and with a quick karate chop he knocked her out.

Standing up he put her once again back on her box. “And stay here!” Kaigaku said, turning his back and having his peaceful sleep.

Notes:
I find Muzan and Kaigaku eerily similar, which is probably reason those two are my favourite characters in Demon Slayer.

Chapter Text

Kaigaku's mission is to find a demon that is killing one person each week in a village. The people believe that there's a killer in the village, so they are all suspicious of each other. The demon corp has sent other demon slayers before but they all died, which is why they send the new turned Hashira Kaigaku.

Arriving at the village Kaigaku was met by individuals that can't trust their neighbours, at first Kaigaku was just trying to see if there's someone in the village who doesn't go out in the morning, or walk in shades.

But a woman decided to shout something as Kaigaku was talking with another woman. “You stay away from her!”

The shout was clear and in seconds Kaigaku was dragged away much to his confusion and anger. “Hey what's the meaning of this?! I'm not going to kill her! Kaigaku exclaimed, now walking beside the other woman. A old man saw this scene and snorted at this, almost like he saw this happening before.

“Are you stupid? The person you were talking to is the most suspicious villager! I just saved your life!”

Kaigaku sighed after hearing that, because he highly doubted that to be the case considering the woman was walking in the daylight as usual.

“And why do you say that? She seemed fine to me.” Kaigaku said, his tone clearly laced with anger. The woman he was talking with was giving him interesting information and he's angered that this woman just ended the conversation.

“Because she's the person everyone in the village suspects to be the killer, or haven't you heard of one man dying every week in here.”

Kaigaku heard in fact that's what the first woman was explaining, but Kaigaku still isn't convinced that the first woman was dangerous specifically because she was sad, and her secret lover died.

“Okay that's the moment I back away, goodbye accusatory lady.” Kaigaku said his voice was poisonous.

“What?! Aren't you hearing me? I said.” Woman was interrupted as Kaigaku put his nichirin blade in the woman's throat.

“Leave me alone… I hate when people interrupt me, and you cut off my other conversation so get lost!” Kaigaku said, and the woman was going to shout but ended up not following this idea and instead ran away.

“Stupid people, with idiotic beliefs.”

Kaigaku isn't happy at all with this town mostly because it seems they're targeting a poor innocent woman, or maybe it's for another reason.

“Dammit! I should have asked her more questions! Stupid.” Kaigaku mutters angrily to himself, truth to be told he just disliked the accusations because it made him remember of the first time he encountered Jigoro, his master and he was in a terrible situation at the time.

But washing away those ridiculous ideas out of his mind Kaigaku returned to his goal of observing the surroundings of the village trying to catch a glimpse of something.

The day passed and Kaigaku found nothing useful in the village with many individuals refusing to even talk with him, some warned Kaigaku to be careful and others blamed the same other woman as the most suspicious.

It was enough for Kaigaku to completely remove the woman from the list, viewing her as just an innocent woman that people are blaming for bad situations.

But at night Kaigaku decided to continue exploring the village in hopes of either being attacked or hearing someone being attacked, he wasn't worried which option happened.

But as the hours passed with Kaigaku wandering the streets of the village he was starting to get bored as he wasn't hearing any shout and nothing appeared attacking him.

But just when he was ready to just give up on the search for this night, thinking it would only attack the following night, he heard someone shouting for help.

“Finally some action.” Kaigaku says to himself and immediately darts towards the location of the shouting and arriving there he can only see a man trying his best to run and he can only see the back of the demon, who's wearing a yukata.

“Hey stop there demon, it's time to die!” Kaigaku shouted and went for the attack but the demon didn't move and when Kaigaku was going to cut the neck.

The demon teleported, making Kaigaku swing his sword in the air. “What? Of course, it knows kekijutsu.” Kaigaku muttered to himself, sheathed his nichirin and looked at the man.

Only to see that the man was also gone. “Well I suppose I have to wait until next week.”

With that Kaigaku walked away, already making the plan of how he could possibly capture a demon with such sneaky kekijutsu, but Kaigaku was expecting to capture it easily, after all the demon isn't even a lower moon so it should be easy.

With that Kaigaku went to sleep somewhere into the night, only for him to be encountered by the same woman he heard many people accusing of being the responsible.

“Are you going to sleep outside, young man?” The woman said and Kaigaku looked at her confused since it was rare for people to walk at night in this village, the man who died was probably just a guy who wanted to prove himself and capture the killer.

“Yes I don't have a problem with it, besides maybe the killer will come for me instead of me coming to him.” Kaigaku said and he missed how the woman smirked at this comment. “The question is what you're doing here lady.”

At this the woman chuckled and sat beside Kaigaku much to his discomfort as he put a good distance away from her.

“I'm looking for the killer as well, but I'm starting to lose hope of finding it today once again.” She said and Kaigaku thinks it's unlikely the demon will attack a woman at least for now. “But you shouldn't sleep in the street, how about you sleep in my house until you encounter the demon?”

To this Kaigaku raised an eyebrow, never in his life had he encountered such a good person… Well before he encountered Tanjiro, the situation was very fishy in Kaigaku's mind.

“And why would you let a stranger sleep in your House?” Kaigaku asked, eyes narrowed and for the first time he became wary of this woman, she may not be the demon, but she can still be a killer.

“I want to help a demon slayer like yourself.” She said, which surprised Kaigaku but looking down with what Kaigaku figured is a sad face she continued. “The demon already killed many innocents and you will be stronger with a good place to sleep.”

This answer was enough to satisfy Kaigaku, because in his mind due to what he heard of the woman he subconsciously put her as a misunderstood person.

“Sure then I might accept, but how do you know of the existence of demons and demon slayers?” Kaigaku asked as the two got up from the ground.

As the woman guides Kaigaku in the street, she decides to answer his question.

“My father was a demon slayer, he got critically wounded and retired, so raising myself he told me about them, but he refused to teach me breathing techniques.” She said, having some pause in her response like she was thinking about something.

“I see, that's unfortunate but which breathing did your father know? And is he still alive?” Kaigaku said, and this made the woman widen her eyes but she composed herself.

“He used flame breathing and he's dead. Died from an illness, a few years ago.”

At this Kaigaku nodded his head and the two continued walking, it didn't take long for them to arrive at the woman's house, in the way Kaigaku learned that the woman calls herself Yuki.

Arriving at the house Kaigaku noticed it was a small house clearly made for a small family with the maximum of a single child.

She showed him where her room is, where Kaigaku can sleep and a room where he can't enter no matter what and Kaigaku accepted easily.

Now he's in the futon that was given to him and he's ready to fall asleep. “What a nice person, she's not. She wants the demon dead as quickly as possible so she will make me not suffer, she's smart and understands I'm powerful, so she's fine.”

With those thoughts Kaigaku went to sleep, with no problems in his sleep.

The following days, Kaigaku's continued his investigation towards the town trying to see if he will get some type of clue but it seemed that those villagers are obsessed with Yuki being the culprit something Kaigaku knows isn't the case.

He also stopped investigating at night since he knows the killings happen only once a week so he just needs to wait for the next week.

So now we arrive at the morning of Monday, the start of the next week so Kaigaku can continue to investigate at night.

At the moment he's having breakfast with Yuki, who's always trying to take information out of Kaigaku from his past and such, he never inform her about it since he's not going to trust a stranger so easily.

After the breakfast he once again tries to talk with the people in town, still trying to talk with the people who's avoiding him.

“There he goes again, trying to get information.” A villager said to a elder who was sitting at the front of his house.

The elder sighed and thought that he should make the stop his useless pursuit because he knows nobody will talk out of fear for their life.

“Time to save this boy life.” The elder said standing up, much to the younger adult near him shock.

“Father you can't, remember about the thing.” The younger said, but the old man didn't care and continued walking.

The young man, just clenched his fist and hold back tears, because he knows the old man will die that night.

The truth is those who don't talk are the ones who saw the demon face and are under protection, but they can't escape the village.

“Hey boy! Stop pestering the quiet ones, I will answer your questions.” The old man said, and Kaigaku hold back a sigh of relief because he was getting tired of those cowards not talking to him.

“Alright, old man. Then can you say to me who do you suspect to be the killer except for Yuki.” Kaigaku said, and the old man smiled at the last part od the conversation.

“Good you already in the right track, but the killer is that woman who made you stop talking with Yuki.” The old man said, and Kaigaku almost rolled his eyes since this woman while annoying can walk in the sun.

But then Kaigaku stopped on his tracks since his mind have found a possible solution. “Say old man, does this woman have a husband, or close relative alive?”

The old man pondered for a few seconds why Kaigaku would ask such a question but he answered lightly. “From what I know all of her relatives have died, but she does have a husband but the man haven't been seen for a while, she says he's sick.”

At this Kaigaku breathing stopped and he clenched his fist, in anger not towards the woman but at himself for not entertaining the idea of a human helping the demon.

In hindsight this should have been obvious, after all Kaigaku himself helped a demon in the past but still his was a one time thing and he was a child, so an adult helping a demon was something he never encountered before.

But regardless of his mistakes he now knows exactly what he should do and he will do it quickly and efficiently.

“Thanks old man, I promise to stop the killings today.” Kaigaku said, to the old man walking away towards the house of Yuki.

Now he only needs to wait until night arrives, and so when the sun finally settled down, Kaigaku went immediately in the direction of the house his target.

Arriving there he opened the door slowly, his nichirin blade in hand, walking slowly he was surprised to hear nothing from inside the house.

He just walked until he arrived at a room, where he slowly opened the door, only to see the woman that he has been searching all this time, laying on the bed, crying.

“You're here… did you came to kill me?” She said, with a weak voice, that made Kaigaku confused because never before he was expecting this to happen.

“Not really, I don't kill humans. I'm searching for the killer, who I believe is your husband.” Kaigaku said, avoiding the word demon, just in case this woman really is clueless about the situation.

He heard the woman sigh and she sat up, Kaigaku was expecting her to say something but the silence continues.

It became too much for Kaigaku to be staring at the woman. “So are you going to say something or we're going to be in this staring contest.” Kaigaku said, not trying to be rude but he was not liking how things are going.

The woman looked at him with so much sadness in her eyes that Kaigaku almost wavered because he recognises this look, from someone who's lost with nothing to do.

However what's truly marvelous is that he never before saw this womab wearing such sad expression before, since he often saw her in the streets.

“You're correct, that the killer is my husband.” When the womab said this Kaigaku relaxed a little, since this mean he's correct. “But you won't find him here.”

This confused Kaigaku, since he's confused about what she meant by such a thing, since by the previous actions of the demon he never kills in Monday.

“If he's not here then were else could he be?! Aren't you the one that's helping him?!” Kaigaku said his voice was now at shouting level, and he was starting to get nervous because he thinks he knows where her husband is located.

The woman didn't answer immediately she just looked at Kaigaku with look of pity as she saw Kaigaku expression is fearful as if he doesn't want to believe his mind.

“He's at Yuki house… I'm just the pawn used to kill those that come looking for them, I'm actually surprised you came here today they often.”

The woman didn't finish her phrase because Kaigaku started running he exited the house and immediately put his sights into the house he slept for the last days.

Kaigaku mind is filled with rage, not the benevolent kind but the rage of being played, and he won't forgive anyone who tries to manipulate him even a human will die for such audacity.

It didn't take long for him to arrive at the house and he entered with violence going to the only room, Yuki told him not to enter.

Upon destroying the door, the first thing he saw was the demon with his long black hair, and Yukata having a meal like a human, from what Kaigaku believes is a human organ, and sitting in front of the demon is Yuki clearly indifferent to the situation.

“Look at this, the demon slayer is ready to kill-”

The demon didn't finished because Kaigaku attacked him immediately leaving no room for talk, but the demon teleported.

“You're more aggressive than the last ones but, if you attack me she will die.” The demon said, having Yuki as a human shield.

“So what you're saying is that if I attack the two of you will die.”

“Exactly boy, and you don't want innocent Yuki to just die right?”

Yuki eyes were scared and a tears are escaping her eyes. “Please Kaigaku-san, save me.” She begged for Kaigaku, with her voice dripping with sadness and fear.

“Third Form Thunder Swarm” Kaigaku muttered and in a flash he went besides the two and started moving around spinning and giving arched slashes in all directions of the pair.

When he finished the move the demon had lost one of his arms and was at another location of the room, while Yuki is decapitated and dead, this being the first time Kaigaku ever killed a human.

This for anyone would bound to make them waver after all he's a demon slayer not a person that does justice. Kaigaku however just ignored Yuki and looked at the demon, Kaigaku expression is serene because right at this moment Kaigaku understood everything.

“You crazy bastard! You just killed my love! And a human! Aren't you supposed to be a good guy?!” The demon is clearly in panic.

“Are you stupid? She helped you, and was clearly having no problem seeing you eat human eat. As far as I'm concerned she's worthless and shouldn't live.” Kaigaku said, his voice matter of fact, he's not showing anger he's explaining how the world works.

“You monster!” The demon said and teleported behind Kaigaku which let him give Kaigaku a punch, but Kaigaku didn't moved and the demon teleported again.

This time he went towards another location, but once again behind Kaigaku, and Kaigaku took the damage, but this time he turned around for an attack and once again the demon teleported behind Kaigaku, but he didn't attack this time he backed away.

For the demon, Kaigaku is just crazy and swinging his sword recklessly.

But in Kaigaku perspective he's seeing that same ghost once again who appeared to guide Kaigaku. “Listen Kaigaku, your mind is in a perfect state. Now do as I instructed and everything is going to work.”

The ghost said and Kaigaku took a deep breath, he was accustomed to do this technique so it might not work, but he will trust the voice.

The demon teleported towards Kaigaku back once again. This time Kaigaku used the third form and the demon barely reacted and the moment Kaigaku eyes registered the demon teleporting, Kaigaku immediately turned around.

“Thunder Breathing: First Form Thunder Flash.” And so in a flash Kaigaku went forward decapitating the demon.

“H-how!!” The demon shouts and Kaigaku dropping to the ground decides to answer this question.

“Very simple, no matter what you never teleport to where I'm looking and you never teleport away from thia room, at this the rules of your technique became simple.” Kaigaku said, his voice calm.

“Still, if I let you devour more humans your technique would become a real problem that I'm sure of it.” Kaigaku said, this being the most praise he ever said to a demon, not long after the demon died completely.

This time Kaigaku looks in the direction of the ghost haunting him for a good time. “So are you going to introduce yourself and tell how you know how I was failing to use the first thunder breathing form?”

The ghost continued expressionless but Kaigaku has a faint feeling that the ghost is amused by this. “Not being rude but you had a terrible teacher, if he couldn't point out how you were putting your foot in the wrong place, and how you were breathing wrong.”

At this Kaigaku narrowed his eyes because the ghost avoided one of Kaigaku's questions. “Yeah my teacher favoured the coward over me, it's no doubt he would actively try to hinder me. But you still avoided my first question.”

Hearing this the ghost felt bad for Kaigaku because from what he saw in Kaigaku dreams the boy suffered which explains how he could easily kill a bad human upon seeing Yuki, but hearing that even Kaigaku teacher favoured another student makes the ghost feel even more bad for Kaigaku.

“My name's not important but if you want to know, I'm Yoriichi. You likely don't know who I am, but I was there when breathing first started to appear.”

Kaigaku is now very interested in learning about this ghost and why he's following Kaigaku.

“I see, but then why are you following me, teaching me. And always wandering in my dreams.” Kaigaku asked, sitting in the ground since he feels this is going to be a long conversation.

“The book you picked up was written by me, and after I died it seems I was with responsibilities in the world so my spirit continued in the world, wanting my wish to ve fulfilled.” Yoriichi said, again he continued expressionless but Kaigaku can feel that Yoriichi is filled with regret.

“I see and what type of mission you need to accomplish?” Kaigaku asked, his voice was softer than usual and he hesitated a little.

“I have two, I will keep one of them a secret but the other is to kill the demon progenitor.” Yoriichi said, and Kaigaku gave a weak chuckle.

“And you're preparing me to do it… That's alright I'm a Hashira now. Still do you think I can beat him.” Kaigaku asked and even before Yoriichi talked, Kaigaku felt that Yoriichi is fearful so he imagine the answer is a negative.

“No, even with my training you will fail.” Yoriichi said, but he hesitated to continue talking as if unsure that Kaigaku need to know the rest. “However, I can prepare your body to be stronger than it should be, it's my duty to kill the progenitor. With time your body will become like mine and with time my spirit will merge with yours and my destiny will be your destiny. However it will take time and I will need your approval.”

This was too much information for Kaigaku to receive at once so he took deep breaths. “So you will just vanish forever, that doesn't sit right with me.” Kaigaku said, the words leaving his mouth without his brain permission, because Kaigaku knows this would be a great thing for himself as he will get stronger.

“Yes, that's what I must pay for failing to save people 3 times, it seems fair.” Yoriichi said, and he started to fade, something Kaigaku noticed.

“What's happening? You can't disappear yet!” Kaigaku exclaimed and then he saw Yoriichi giving him a smile.

“It's alright, it's just that I can't stay too much in contact with you. I will appear in your time of need, but until then try to control your bloodlust and fight with a calm mind. That's the first step.” Yoriichi said, disappearing completely.

Wirh this Kaigaku reached his clothes and picked up a old book from it. “So this was yours Yoriichi. You seem like a nice person, and you believe in me different from the old man, so I will make sure to show how great I am.” Kaigaku said, walking away from the town.

With this he didn't even checked on the woman that now lacks a husband, because he doesn't care about any of that, however this mission gave Kaigaku a important lesson on who, he should trust.

This was a lesson that Kaigaku will remember, because he now understands that sometimes people are correct and that he's not going to always be correct about things.

(If you are confused about anything that happened in this chapter you can ask in the comments and I will answer, since I read those, even if there's only 4 at the moment.)

Chapter Text

Kaigaku returned towards Ubuyashiki mansion where he was informed that he now have a living location of his own.

Kaigaku thanked them and went towards his new home and opening the door was a task itself he was shaky why he's this way we're going to discover later.

But as he entered the mansion he took a deep breath, exhaling and letting out a small smile out of his face.

“A house of my own, for the first time.” Kaigaku muttered to himself in a happy tone.

Kaigaku is happy at how things worked out for him, he always knew he was someone with great talent, certainly more talent than those he was surrounded for most of his life.

But he's glad that those in the demon corps have a good estimation of his of his worth, different from Jigoro who dared put Kaigaku in the same pedestal as Zenitsu.

But that's things from the past, he will now focus on organising his new residence.

As he was doing that his crow appeared. “You're lucky I kept my mouth shut Kaigaku!” The crow shouted and Kaigaku knew exactly why it was saying that.

“What could you be talking about? The woman was killed by the demon and I could do nothing about it, as I was too far away to save her.” Kaigaku said, not going to admit his actions, specially considering the fact he did that in the despair of the moment.

It wasn't planned, but it's not like he feels guilty about it, the woman was evil and he eliminated evil. It's simple and easy, he's not like the fools in the upper ranks, that views all demons as evil and all humans as good.

He remembers how Jigoro taught him that demons must be killed without a second thought, that he would be surprised of why Zenitsu didn't kill Nezuko, but he then remembered that he's thinking of Zenitsu the coward Zenitsu, the idiot Zenitsu.

But that's besides the point Kaigaku doesn't like to think about things that doesn't concern him, and how the demon slayers view demons is none of his concern, after it's not like he cares about demon thoughts he kills them, because they hurt humans and he's a human, end of discussion.

But as the hours pass and nighttime arrives, it's finally time for Kaigaku to rest as he finally ended to organise his residence.

“Oh almost forgot to say, you have a new mission tomorrow! Accompany the flame Hashira to to a train where people are missing, you will also be accompanied by three other weak demon slayers!”

Kaigaku crow shouted, making him sigh but just enter his bed, now knowing he already have a new mission, although he wonders why they're sending two Hashira.

In the following day Kaigaku woke up early in the morning as he knew that honing his skills before the mission is essential.

But in his training he can't help but wonder what Yoriichi meant by merging as Kaigaku had many questions for Yoriichi but unfortunately the man couldn't answer due to time limitations.

Which is something that frustrate Kaigaku but again there's nothing he can do about it so he decided to accept his unfortunate circumstances.

But as the day went forward it's finally time for Kaigaku to meet with Rengoku for their mission together.

When the two encountered eachother, Kaigaku saw the high mood of Rengoku, which Kaigaku just ignored, but something is in Kaigaku mind ever since he received this mission.

“Rengoku-san.” Kaigaku said, with the san going in a very forced manner as Kaigaku didn't want to say it due to not respecting Rengoku. “Could you explain to me, why they're sending two hashira in this mission, where it's only suspected to have a lower moon?”

Rengoku heard this and quickly explained. “That's simple young Kaigaku, since you're a new Hashira we want to test your abilities being watched by an experienced Hashira, and due your actions against Shinobu apprentice, some Hashira don't trust you!”

Kaigaku nodded his head in understanding, but judging by the fact Rengoku felt the need to mention his actions against Kanao, it's obvious that him being a new Hashira is the lesser factor, so this made Kaigaku click his tongue clench his fists, this certainly will be remembered.

As the duo arrived at the train station, it didn't take long for them to enter their train. With Kaigaku sitting into the neighbour seats instead of sitting besides or across Rengoku.

Not long after Tanjiro and his crew arrived, there was a uneasy glance that Zenitsu gave to Kaigaku, either it was fear, respect or hate, Kaigaku didn't care.

Tanjiro greeted Kaigaku with a happy tone that Kaigaku wasn't interested in dealing when they're going to fight a demon soon enough, so he just greets Tanjiro back and says for him to talk with Rengoku, which thankfully Tanjiro did as it seemed he had something to talk with Rengoku.

The other two didn't bother Kaigaku, as Zenitsu knew the futile of things, while Inosuke wasn't interested by Kaigaku so things were peaceful.

As soon enough the train started moving and in sequence the conductor appeared checking out the tickets of the passengers.

Kaigaku wasn't triggered by the guy although he certainly found his appearance weird and suspicious, but he did nothing as he could be wrong.

So next thing Kaigaku knew he was talking with Jigoro, and this made Kaigaku jump away.

“Where am I?! What are you doing here old man?!” Kaigaku exclaimed, purely confused. But Jigoro just looked confused to Kaigaku.

“What are you talking about Kaigaku? We're just discussing he how it's a good thing that my only apprentice became an Hashira.”

This phrase should have made Kaigaku even more confused, but instead it calmed him down as if understanding things.

“Right, I just was imagining bad things as usual master.” Kaigaku said the words coming out of his mouth in a weird way.

And in another location inside this dream world, Yoriichi is confused with this.

“A kekijutsu… but it seems this is rather useful, maybe I can interact with you freely here.” Yoriichi said, but before he could walk further he felt someone approaching Kaigaku spiritual core.

Chapter Text

Kaigaku kept talking with Jigoro as if nothing was wrong, eventually Tanjiro and Nezuko appeared, with the two also talking with him.

But something felt incredibly wrong in Kaigaku's opinion because despite everything in his mind, things weren't supposed to be so peaceful.

But the ones watching him noticed this, no rather it was the Tanjiro in this dream world that noticed something wrong with Kaigaku expression.

“Is something troubling you Kaigaku-san, you seem too tense when we're merely commemorating you achieving the rank of Hashira.” Tanjiro said, but this did nothing to make Kaigaku more at ease.

In fact it did the opposite, only making Kaigaku feel even more uneasy as if he's missing something, as if the Tanjiro that he knows would not just celebrate things like this.

“Kaigaku-san, tell us something you being all silent is concerning.” Nezuko said, making Kaigaku feel even more at ease, this Nezuko is stiff around him, being far too polite.

Somewhere in Kaigaku mind, he feels that something is wrong but instead of saying or doing something he just keeps quiet and thinks of why he's feeling such a weird emotion.

But right on the location of Kaigaku spiritual core, there's a intruder a kid that the demon responsible for the dream sent to destroy Kaigaku Spiritual core.

Kaigaku realm of unconscious has a interesting appearance, it's a thunderstorm with a big sun in the top like it's midday, the place is completely colorless even the sun and the kid who just entered is also slowly losing colour, and if he stays there any longer he will become empty of emotions.

So the boy quickly located Kaigaku spiritual core, it didn't take long for it to appear but right when it was going to destroy it, Yoriichi appeared and with a katana cut the boy hand off.

“Apologies for your hand but I will ask for you to not destroy my host mind.” Yoriichi said, his voice expressionless and in a instant he cut down all the limbs of the boy, making him scream.

“Don't worry about the injuries, once you return you will feel like nothing happened.” Yoriichi said, deciding to try and locate Kaigaku.

Why Yoriichi is here is quite simple, due to having took over control of Kaigaku body once, Yoriichi now passively lives inside of Kaigaku unconscious realm.

It's also why there's a sun in there, it appeared after Yoriichi first took control over Kaigaku body, without Yoriichi there would be no sun.

But it was within seconds that Yoriichi appeared towards Kaigaku who upon seeing Yoriichi got extremely surprised, but above all it finally made Kaigaku notice he's got in a dream.

“Yoriichi! A demon is attacking me right?!” Kaigaku said, and in that moment things warped and he was put into another place.

This time however Kaigaku already more aware of things got his nichirin blade back, and in that same moment he killed all of those dream people without hesitation.

“Get out of my way, you fake people!” Kaigaku said, rushing out of the house that he was put searching for Yoriichi, whom Kaigaku believes it's not part of the attack.

It didn't take long for Kaigaku and Yoriichi to encounter each other.

“Kaigaku, you had questions before, so ask them, but be quick I'm certain you know why.” Yoriichi said, and while still expressionless, Kaigaku could feel that Yoriichi is with a certain urgency to do this.

This being something that Kaigaku thinks is due to the nature of this situation being the result of a blood demon art.

“What did you mean with my body getting stronger? I'm certain that training will be enough right? If not then which breathing style is my body adapting?” Kaigaku said, already having a good guess to what Yoriichi meant, but still lacking fundamental information.

Yoriichi for his part gave a faint smile and answered the question. “It's my own breathing, in my life I didn't see anyone who could use it with perfection other than myself.” With that Yoriichi stopped and seemly started remembering the past.

At this Yoriichi faint smile vanished returning to his usual expression, but Kaigaku could tell that Yoriichi isn't reminiscing good memories, it seems like a very sad thing.

“My breathing was called by my companions Sun Breathing, that's what your body is changing into, but this isn't going to make you stronger by default, you will still have to train yourself.” Yoriichi said, and it seemed like he was going to keep talking but his demeanor changed as if he's sensing something.

“Pardon Kaigaku, but our time is over. Your friend has awoken and it would be wise to help him.” Yoriichi said, in response Kaigaku nodded his head and immediately cut off his throat.

Waking up Kaigaku immediately sees a some type of flesh growing out of the seats and in a flash he immediately cut all of them.

At his side he saw Nezuko who was going for a strike towards the flesh but stops upon seeing Kaigaku awake.

“Nezuko, I will let you take care of this part.” Kaigaku said and immediately darted in direction of another train car, fearing that this is happening in all of the train.

When he arrives there he immediately sees that he was right and goes immediately to cut it off, Kaigaku was being nervous since he thinks the others are still sleeping.

But it doesn't take long for Rengoku to appear in front of Kaigaku having a smile on his face that contrast with Kaigaku scowl.

“Kaigaku, I already spoke with the others, so I will say it to you, the yellow boy and Kamado sister are defending one of the train cars, Kamado and Inogashira are looking for the demon head, while the two of us are going to take care of the remaining 7 cars.”

When Rengoku said those words Kaigaku nodded his head and in flash both men disappeared from their location.

Kaigaku did the work with extreme diligence, stopping the demon to even touch one a single person, he wants to show Yoriichi that Kaigaku has what it takes to be the successor of his will.

It was after a few minutes that suddenly the train went off the tracks, Kaigaku figured that Tanjiro had cut the demon's head.

But regardless of this Kaigaku was quick to start doing several of his breathing techniques to minimise the damage on the train cars.

On his way of doing this he noticed that Rengoku was doing the same, but it was thanks to this detail that Kaigaku noticed the difference in their skill.

Rengoku movements were even more precise than that of Kaigaku, it also had much more strength, one may attribute this to age which is correct but not due to the development of their bodies.

Kaigaku lacks experience in real combat something that just by looking at this makes it obvious to him, this infuriates Kaigaku, because despite him being a Hashira he still have a long way to go.

And it's his clear weakness that makes Kaigaku takes a misstep, it was due to the movement and the fact he was thinking of other things, regardless this misstep made Kaigaku slip and hit his head.

In the end demon slayers no matter their strength, are only humans a good hit in the head is enough to make them lose consciousness.

When Kaigaku awakes he immediately tries to look for the others and it's in that moment that he sees a demon with his right arm through Rengoku stomach.

Kaigaku reaction is instantaneous. “Thunder Breathing: First Form Thunder Flash.” With that Kaigaku goes forward aiming for the demon head, but the demons notice it.

And so a shock happens with the demon having cut off his right arm, but that doesn't mean Kaigaku didn't damaged Akaza quite in fact, Akaza lost his left leg when he jumped out of the way.

“Another strong human appears, although from the looks of it you're weaker than the other one. Are you also a Hashira?” The demon said, and Kaigaku tensed looking into the demons eye.

“I'm the Rumble Hashira, Kaigaku.”

“I'm Akaza, tell me Kaigaku why don't you become a demon? I offered the same to that other Hashira but he rejected, are you going to do the same?” Akaza said, and for Kaigaku time seemed to have stopped.

A little voice in the back of his head whispered for him to accept because he will die, that if Rengoku lost then Kaigaku stands no chance against Akaza.

But Kaigaku snap out of this bitting his lower lip until blood is drawn, with that he got out of such thoughts, Kaigaku now has people that he doesn't want to disappoint, those being Yoriichi and Kaigaku can't pinpoint who's the others, and why would he think anyone other than Yoriichi cares for him.

Kaigaku is being stubborn of this situation not wanting to accept that a certain pair of siblings has made him soft.

“Sorry but I can't accept, I have some people who are counting on me.” Kaigaku said, and immediately used the first form of thunder breathing.

When he closed the gap in distance he immediately went towards another move. “Thunder breathing third form; Thunder Swarm.” Kaigaku said, immediately starting to spin around Akaza.

Akaza tried to dodge it but the sheer speed of things made it difficult to dodge fully, but all of Kaigaku slashes missed Akaza neck.

By the end of Kaigaku spin, the only thing that , Kaigaku noticed was a hand almost hitting his head, but Kaigaku immediately used the first form of thunder breathing dodging by the neck of his hair.

Unfortunately for him Akaza immediately caught up to him, and used one of his destructive death move.

Kaigaku then used thunder breathing sixth Form: Rumble and Flash. And in the blink of an eye he delivered many thrust attacks that parried some of Akaza attacks but ultimately made Kaigaku be pushed back with a great force.

Kaigaku is wounded but he will definitely live to fight another day, but most importantly the sun is going to appear soon, which is something that Akaza noticed.

So Akaza immediately starts running away, Kaigaku planned on going readying to use the first form of thunder breathing, but he was quick to just fall on the ground, noticing that his legs were badly wounded.

“Damnit!” Kaigaku exclaimed, while punching the ground many times, this entire fight was a humiliation for Kaigaku.

He didn't stand a chance against Akaza, and even the moves that he connected didn't felt truly earned.

By the end Kaigaku felt worthless, and didn't even noticed how Tanjiro tried to go after Akaza.

This truly was a losing battle, and Kaigaku was saved by the fact he was knocked out by the train. Otherwise he would be dead, and Kaigaku knows this which is why he's even more frustrated.

At Rengoku last words, Kaigaku was barely listening he just got up trying to see how much damage he got on his legs.

Different from the other three boys, Kaigaku feels nothing towards Rengoku, he barely knew the man, he saw little reason for crying.

Chapter Text

Later Kaigaku returned to the butterfly state in order for his injuries to heal, his wounds are supposed to be all healed in a few weeks.

It's at night that Kaigaku is just wondering how he can get himself stronger, he knows he needs to train even more but everything felt so dull at the moment.

He lost against upper moon three in such a quick way, and Akaza even called him weaker than Rengoku. That stung Kaigaku being admitted to be weaker than a man who died in the combat.

His mind is drifting towards many other alternatives in how to train even more hard on himself, while letting as few time of rest as possible.

It was in those spiral of negative thoughts that suddenly Kaigaku heard his door being opened and so he looked at it surprised, wondering who's visiting him so late in the night.

When Nezuko revealed herself as being the one who opened the door, Kaigaku remembered how before many times she went towards him. Which he believed had stopped but that's very clearly not the case.

He said nothing to her only watched to see what she's going to do, being very curious and without much energy to get her out of the room.

Kaigaku merely sit up on his bed, and so Nezuko walked in his direction going to his bed and sitting besides him, right after she grew herself to be taller than him.

Immediately afterwards she patted him in the head, almost like she's trying to calm him down, having noticed his turbulent thoughts.

At this Kaigaku scoffed taking her hand off his head. “Don't treat me like some type of kid!” Kaigaku said, getting himself away from the bed immediately remembering about his Injured legs.

But he ignored the pain and just walked towards the window, trying to get himself away from Nezuko.

Looking at the window he wonders what would have happened if he accepted Akaza proposal of turning into a demon. He wouldn't be bedridden, and he would be training right in this moment.

Looking at the moon, the only thing that he could think was about the possibility of so much power that he lost, but what took his away from those thoughts was a sudden hug from behind.

It's Nezuko again, not getting the cue that Kaigaku doesn't want her around but right now that was a good thing that took Kaigaku away from his terrible thoughts.

This time he only sighed and slowly turned around to face Nezuko, and then looked up at her since she's still tall, and in there he only found innocent eyes like that of a child who's just trying to help.

While Nezuko upon looking at Kaigaku eyes made herself small again about her natural height, but what she saw on Kaigaku eyes made her hug him tight, while humming some sort of song.

And to that Kaigaku who was so full of dark thoughts, not allowing himself some kind of happiness couldn't bring himself to act rude.

Instead he slowly returned the hug, but his hug was not tight it's actually extremely light, almost like he's unsure if he should truly hug her.

He was moments away from just breaking the hug, because he found it stupid to be hugging a demon, but before he could proceed with such action he took notice of Yoriichi on the room.

Yoriichi was shaking his head, like saying that Kaigaku should go along with the hug while the man wasn't particularly smiling, Kaigaku could feel that Yoriichi is happy with the event.

But just as quickly as Yoriichi appeared, he also disappeared it only was a second worth of time and for Kaigaku that felt like a much longer time.

So with the push of Yoriichi, things for Kaigaku felt much more different and instead of breaking the hug, he slowly gave a true hug to Nezuko, which eventually turned into an tight hug as much as she was hugging him tight.

Kaigaku face after that was hidden on Nezuko shoulder, but sobs could be heard from him. That's the first time Kaigaku cried ever since that humiliation against Akaza.

Those weren't tears of sadness over Rengoku death, those were tears of his own humiliation and how his lack of strength almost made himself die, but also Tanjiro and inevitably Nezuko.

But most of all him being so weak, also meant that Yoriichi goal of killing Muzan would be impossible to accomplish with him dead, and this is the one that stung the most.

He doesn't want to disappoint Yoriichi, especially when he sees that the man burdens himself with so much things, for Kaigaku he must help the man that sees his worth above everyone else.

And so he immediately discard the thought he was having about the possibility of accepting Akaza deal of becoming a demon, because it would mean the ultimate betrayal for the man that trusts Kaigaku.

“Thank you Nezuko.” Kaigaku muttered in the middle of his crying, because it's thanks to her that he can finally see the bigger picture about the situation.

Kaigaku after that outburst felt himself getting tired, and so in the arms of Nezuko he fell asleep. Much to Nezuko panick as suddenly she just felt all of Kaigaku weight falling down onto her.

The next thing that Kaigaku saw it was him being in the middle of a forest and in there he was with clothes similar to Yoriichi, and right in front of him there's Yoriichi.

“Kaigaku, your body has finally started adapting itself towards my breathing, so now I think it's time for you to finally know the moves you will be needing to perform.” Yoriichi said, and so the first thing he did was to perform all the twelve forms of sun breathing.

And Kaigaku looked at it with awe, Yoriichi moving is the greatest form of swordsmanship that Kaigaku has ever seen, and compared to his own movement it felt like Kaigaku is nothing more than a child just swing his sword around.

By the end of Yoriichi demonstration, Kaigaku was certain that this man is something outside of ordinary.

Following that Yoriichi gave instructions to Kaigaku about the tiny details of the techniques of Sun Breathing, although there's one detail that Yoriichi put that surprised Kaigaku.

“Despite knowing sun breathing, you mustn't stop using Thunder breathing, it's something that you're familiar and your body is naturally good at it, so never stop using it.” Yoriichi said, this being by the end of the instruction so Kaigaku was about to wake up.

This information certainly surprised Kaigaku who believed that he should just stop using Thunder breathing, but with those words Kaigaku took it to his heart. But before leaving Kaigaku asked a question.

“Yoriichi-san, why do you have the same earrings of Tanjiro?” Kaigaku said, and that's a question Yoriichi is glad to answer.

“I helped his ancestors when I was alive, and I gave my earrings to them, and I imagine they passed it as a family heirloom. I do wonder if they still know how to use sun breathing.” Yoriichi said, his tone of voice being nostalgic, but it gave Kaigaku another question.

But before Kaigaku could ask what Yoriichi meant by that last part, he felt himself waking up.

Looking around Kaigaku found himself to be on his bed, all tucked up. With Nezuko nowhere to be found.

Kaigaku almost wonders if he imagined the entire situation with Nezuko, but seeing that his window is opened despite the fact he never opened lats night makes him certain it wasn't a dream.

And against all of his better judgment he felt a small smile creeping in on his face, but he quickly put them back in place having his face once again with an scowl.

So with that Kaigaku spent the rest of his day on the room because he still needs to heal his injuries. That night Nezuko didn't return, but she did on the next night.

With that a week passed, with Nezuko appearing some nights while other nights she didn't, but by the end of the week, Kaigaku is well enough to be sent on missions.

So he was sent away and went towards his own mansion that he got after being named a Hashira.

At times he kept himself training but he was most often away doing missions where he was putting usage of Sun breathing which he immediately noticed that's incredibly tiring.

It's not all that bad if he's not doing it all the time, but it's clearly something difficult but he's still working hard.

He also stopped putting himself into too much strain now taking his time to rest instead of training all the time, since he noticed that his body and mind needs some time to rest or else he will get overwhelmed.

When he's without nothing to do he ends up going to talk with Tanjiro and sparring with him, which made him discover about Tanjiro usage of Hinokami Kagura.

Now almost four months later, Kaigaku was sent into a mission to find a demon that apparently has killed many demon Slayer and it's not subtle in his actions.

So arriving at this village where his mission was instructed the place isn't at all subtle, the head of many people are on a spike with the top of their heads opened and the brain being clearly absent. There's also a nichirin sword right besides each head.

Walking around the village Kaigaku noticed the lack of anyone nearby it seems to be a ghost town, which is against the information Kaigaku received, where it was said that the place is filled with humans.

Walking around a little more it didn't take long for Kaigaku to see a shrine, he figured that's the location of the demon so he walked there.

And inside of it what he encountered was many humans bowing to the demon while saying some type of chant. The demon at the top noticed Kaigaku.

“So there's a new demon slayer trying to kill me, I wonder how much more of you I need in order to finally become a upper moon.” The demon said, having stood up and in a flash being besides Kaigaku, and attacked him.

Kaigaku noticed and immediately blocked the attack, having quickly drawn his katana, what Kaigaku noticed is the demon suddenly changed form, before he looked just like a middle aged man.

But now the demon entire body is made out of a diamond-like metal, and from his forearms a blade is coming one for each forearm. The demon is also massive being three meters tall.

“I hope you have good brains boy, the last one tasted terrible.” The demon said, immediately going towards Kaigaku who was ready for a counter attack.

“Sun Breathing: Fake rainbow.” Using this breathing technique Kaigaku with a a high speed twist and spin, he moved away leaving a afterimage and appearing behind the demon.

“Sun Breathing: Raging Sun.” Kaigaku used such technique to deliver two quick slashes towards the demon who had no reaction to respond and immediately got both of his cut off.

The demon backed away and Kaigaku didn't go for a pursuit, instead he just looked at the demon like he's a predator, watching his prey next move.

This has been Kaigaku routine for the past months, never delivering finishing blows in order for him to better understand how to use sun breathing in combat.

For him nothing of that have a challenge, it's all a way to improve his abilities he's so focused on his own training that he completely ignored his surroundings, not noticing the humans nearby aren't running away, but still bowing and chanting.

The demon for his part got enough time to regenerate his arms and went immediately towards a offensive mode.

“Sun Breathing: Burning Bones, Summer Sun.” Using this technique Kaigaku parried the next attacks of the demon, by making a circular movement with his katana.

Next thing Kaigaku noticed the demon jumped back towards one of the humans who's bowing and chanting.

At first Kaigaku was going to purely ignore that and just let the demon eat the human, since he believed it's the human fault for having believed in a demon.

But then he noticed something and that's the eyes of the human, it's dull and lifeless like it's not even aware of the surroundings and then he noticed how nobody seems to care about him being there, or about the fight they're just inactive.

And the he took a look at the human the demon captured and so he finally noticed that it's a boy no older than eleven.

At this moment instead of getting some sort of emotional outburst, Kaigaku merely calmed himself and all of his attention was focused on how to kill the demon.

In this instant, Kaigaku shows no drive, fight instinct, hatred or animosity. Right in this instant Kaigaku understood Yoriichi first lesson, now he only needs to improve himself further to learn the other two.

“Thunder Breathing First Form: Thunder Flash.” Using the first form, Kaigaku immediately went towards the roof of the shrine and aligned himself to go down immediately.

“Thunder Breathing First Form: Thunder Flash.” Using the first form once again, Kaigaku went down right behind the demon.

“Thunder Breathing Second Form: Rice spirit.” Kaigaku used the second form, delivering one slash towards the arm the demon was going to grab the boy, and the second to decapitate the demon, it wasn't even necessary for him to use the remaining three slashes.

Once the demon head fell on the ground he was extremely lost, because everything that happened was done in five seconds.

The demon was going to shout something, but Kaigaku just cut off it's tongue right afterwards.

“Don't annoy me at the moment, I'm revising my decision making of forms.” Kaigaku said, his voice extremely harsh.

But that's exactly what he's doing, since he's trying to see if he could have used another form to better counter act the situation, surely nothing would change if he used another form.

However Kaigaku is imagining if the demon was the same level as himself and if it was necessary for him to optimise his movements even further.

But before he could think any further, Kaigaku felt himself get tackled by not one person but many are hugging him, with everyone also crying.

“Thank you kid! You really saved us! We have a saviour.” That and many other things were said by the people around.

“Can you people give me space! I'm suffocating!” Kaigaku shouted, caring little about the thanks of the people and just wanting to make them stop overwhelming him.

“You can't do that you brute, we're thanking you!” Someone shouted, with the sentiment being shared by many others since they didn't backed away no matter the words Kaigaku was saying.

An hour later, things calmed down a little, with people giving him space, except for three kids one being the one Kaigaku directly saved from the demon, his younger sister, and his younger brother, they're clinging on Kaigaku no matter what he does.

A part of Kaigaku just wants to take them off himself, but another part isn't that bothered by it.

But it's with those circumstances that Kaigaku got explained that the demon was using it's blood to fully manipulate the mind of the villagers to the point they were just watching their bodies because controlled.

It was a terrible thing that they all had given up hope of ever being free, and when Kaigaku heard about the fact they have been under this control for three years, it was certainly a big shock towards Kaigaku, who at first almost gave an apology.

But he quickly takes control of his mouth and stops himself, in fact he's confused why he would apologise for something completely out of his control.

The villagers wanted Kaigaku to stay for the rest of the day but Kaigaku declines the offer and immediately goes away not wanting to get any more praise, it's something that he certainly appreciates but not to that extreme.

While he leaves the village, he's told that they will remember about Kaigaku for the remaining of their lives and will pass down to their children, and that Kaigaku will always be welcome in the village.

Chapter Text

Kaigaku arrives at a more modern city than that of the last places he went before, for Kaigaku the many lights are a little distracting, but nothing that he never saw before.

He went to this place just for a little stop until he returns for him to rest, at this he went to a hotel where he's going to stay the ngith.

There he decided to read the last letter he received from Tanjiro, he received a few days ago but only now he had the time to read properly.

The contents of the letter explain mostly about Tanjiro lats missions, and the last part commented about the fact Tanjiro, Zenitsu and Inosoku are going to the Red light district with the Sound Hashira.

Kaigaku didn't write back to Tanjiro, despite Tanjiro always writing letters to him, not even once did Kaigaku write back, not seeing any reason to write back.

It was only a few minutes later that Kaigaku decided to explore the city for a while, he wasn't tired yet so he thought that a little bit of exploration might do him well.

While walking Kaigaku reflected on everything that happened in the last few months, a lot of things happened to the point Kaigaku feels like he changed a lot.

It almost feels like he can be happy for long periods of time now, instead of his happiness just drifting away not long after.

But for that he thinks that it might be just his impression but at that two faces appear on his mind, and before he can think further he hears a scream.

So he quickly dashes in the direction of the scream, making sure that his hand is near his nichirin blade, so that he can uses the first form of thunder breathing, in the case of the responsible being a demon.

Upon arrival of the originator of the scream, Kaigaku found a man on the ground with a look of pure horror, the man is staring at a skeleton who's laying on the ground, and is clearly fresh due to still having a few flesh still on the skeleton, and bite marks on it.

“Hey what happened here!” Kaigaku shouted, making the man stand up but what followed was the man stammering and Kaigaku was angry, but breathing deeply Kaigaku decided to not react as he typically would.

“Compose yourself! Take deep breaths and tell me slowly what happened, it's okay I'm qualified to stop the threat.” Kaigaku said, but the words he said felt incredibly wrong in his mouth, but he won't take it back now.

It took a little while for the man to compose, but when he did obeying Kaigaku terrible instructions to take a deep breath, the man was just calm due to Kaigaku katana, uniform, and his clear strong body, and calm under the situation.

“...I was just walking the street, when I saw something on that tree, and suddenly the thing threw to the skeleton in the ground.”

With this information Kaigaku, confirmed what he already suspected to be the act of a demon.

“Good but don't talk to anyone about this old man, you don't want the others to panic, don't worry I will deal with this quickly.” Kaigaku said, and he didn't really wait for anything else he just went to search for the demon.

He stayed the entire night trying, to find any hint about the demon, even when he noticed the lack of hints he kept searching in hopes to stop another attack.

But when the first rays of sunlight appeared, Kaigaku decided to stop searching, take two hours or four hours of sleep, then he will try to interrogate the people, in search of anyone suspicious.

A few hours later

Kaigaku investigation wasn't heading towards a lot of help, since people didn't seem to find anything strange, and also the fact that the killing from the previous night was from what Kaigaku researched the first one.

Which Kaigaku deduced a new demon was created, or a old demon is changing his hunting grounds.

By the afternoon, Kaigaku was positive over the fact that nobody knew a single information about suspects, until a he met a young boy.

“There's the Muto family, things with them are often light hearted and they always make their presence known, but recently they have been quiet.”

This piece of information that Kaigaku received made him approach his next questions in a easier manner.

So with that he went around asking about the Muto family, and people were more engaging now that Kaigaku had a something of substance to ask.

“So let's see, the Muto family is a family of merchants, they're often engaging but now they're hiding in their house, and their son was sick.” Kaigaku said, to himself recapitulating all of the events that happened.

With that Kaigaku started walking in the direction of the house of the Muto family, for him it's clear that he just needs to enter the house and kill the demon inside.

Arriving there Kaigaku soon discovered that the house is big having two floors, so he jumped and crashed into the window of the second floor.

He found himself into a empty room, that's gathering webs in the corners, he walked out of the room, searching for any sign of someone in the house.

Walking for a few minutes Kaigaku got to quickly find two individuals, a man and a woman with the man holding a katana and ready to enter a room.

“That's a stupid decision, don't go around throwing your life away.” Kaigaku said, making the couple startled and look in his direction.

“Who are you?! How did you get in?” The man said, ready now to defend himself.

While Kaigaku is unbothered by the situation and just walked in their direction.

“I'm a demon slayer, and I'm going to kill your son, and you will fail in doing that do scram!” Kaigaku said, but the parents didn't went away from the door although the father did let the katana fall in the ground.

“If you're a demon slayer then you must kill us! This is our fault for despairing and for allowing that man to help our son.” The mother said, taking Kaigaku by surprise, but the boy was quick to get angry at their request.

“Oh you guys want to die, it's my pleasure to deliver it!” Kaigaku said, and rushed towards them, not to kill them. Kaigaku merely knocked them out.

“Idiots, your life is a sacred thing always fight for your survival no matter what, should have just run away from here the moment you knew about your son change.” Kaigaku muttered, opening the door to the room where the demon is located.

“I SAID TO GO AWAY!” The demon inside shouted, not realising that it wasn't his parents that entered the room.

“Thunder Breathing First Form: Thunder Flash.” Using this technique it was a clean shot that the newborn demon couldn't even react before getting decapitated.

“Yeah well it's always nice to find a weak demon, and put them in their place.” Kaigaku said, already walking out of the room being very indifferent of the situation.

But in the way out he remembered of the parents who were about to kill themselves, so he looked for a paper and something that he can write.

After finding he wrote; Don't kill yourself, or get punished otherwise I will pursue you two in hell once I die, just because your stupid son turned out to be a useless demon, it doesn't mean you also should die like useless people, so just give birth to another one.

Finishing to write that, Kaigaku put the note on the top of the man body, and walked away, wondering what he should be doing next.

A Few Days Later

Kaigaku returned to the butterfly state purely to check a wound he received after being careless and underestimating his opponent.

A flaw of his that Yoriichi thinks will one day be the death of him, so the ghost of Yoriichi made sure to remember Kaigaku do stop underestimating his target.

But Kaigaku can't help it, those demons are all now so weak that he can't bring himself to fight seriously. Even more he wants to improve.

After that first night where he used the Transparent World, Kaigaku never again was capable of using it again, which frustrates him because it feels like he's not giving his all.

The selfless state is another situation, Kaigaku by now can use it whenever he's silent, but the moment he talks all of his attack intention appears, so fighting he just keeps silent.

But upon return he got the news that upper moon six was killed by Tengen Uzui, Tanjiro, Inosuke and Zenitsu. And due to the fight Uzui is going to retire since he lost one of his arms.

So it was at the night that Kaigaku decided to visit Tanjiro on his room, Kaigaku didn't went in the morning due to not wanting people to see him there.

“Heard you and the sound Hashira defeated Upper Six.” Kaigaku said, while opening the door to the room and standing over Tanjiro who's laying on the bed awake.

“...Inosuke and Zenitsu were also there to help.” Tanjiro said, weakly due to his injuries, but what he said made Kaigaku scoff.

“No need to lie about it, while I'm certain boar boy helped in some way I'm willing to bet he helped the upper moon more than he helped you guys.” Kaigaku said, with Tanjiro about to say something in return but Kaigaku stopped him.

“But I didn't come here I to talk about your mission, I want to know if you're alright Tanjiro.”

“I'm alright, probably going to be back on my feet, in a few days.” Tanjiro said, in such a quiet manner that Kaigaku noticed.

“Well you fought a hard opponent, so rest well Tanjiro.” Kaigaku said, leaving a little food package on a table nearby.

Tanjiro was going to call to ask Kaigaku what it have but Kaigaku turned fast without letting Tanjiro see his face.

“That's food to help you recover, don't think it's anything special I just made too many for myself!” Kaigaku said, and so he walked out of the room without looking back.

Walking on the hallways of butterfly manor, Kaigaku’s thinking of what he can do in order to improve his technique.

So he went outside, taking some deep breaths before he starts trying to do what he went there to be doing, Kaigaku felt someone tugging the back of his clothes.

Looking back Kaigaku found Nezuko there, looking at him and he just stared back at her, not certain what he should be doing.

“If I'm not mistaken Tanjiro said you like this.” Kaigaku said a little confused, so he slowly put his hand on Nezuko’s head and patted her head, it was a slow movement Kaigaku was uncertain what he should be doing.

It was just something he heard Tanjiro saying, so with Nezuko not giving any reaction Kaigaku was going to take his hand away and apologise.

But just as he was removing his hand, he felt Nezuko own hand stopping him from take his hand back to his possession, and with that he kept doing it.

When he saw Nezuko closing her eyes and leaning into him, Kaigaku just kept doing, the hesitation he was feeling before was now completely gone.

A small smile even formed in Kaigaku face, it was such a little smile that he didn't even notice it.

“I heard you helped your brother Nezuko, and healed the poison inside their bodies. That's good you're proving all those Hashira wrong, I would pay a lot of money just to see their faces after what they said about you and Tanjiro in that meeting.” Kaigaku said, what started as just praise became a way for him to belittle those he thinks are inferior to himself.

But he didn't kept that topic instead shifting to another thing since he's still smiling.

“You know, you always appearing near me is a confusing thing, does Tanjiro ask you to come or it's just your instincts?”

Kaigaku knew there would be no response since Nezuko doesn't talk back due to what he thinks is the hypnosis they did on her.

So he stops patting Nezuko head, and instead lay on the ground, looking at the stars.

“Come I want to show you something.” Kaigaku said, and Nezuko immediately listened to him laying down right next to him.

"Look," Kaigaku said, pointing his hand towards the north. "See those seven stars that look like a ladle? That's Hokuto Shichisei. The two at the front of the cup, draw a line through them."

While saying that Kaigaku moved his hand to point a single, unblinking star. "Polaris. No matter where you go, no matter how lost you feel, she is always there. Always north.”

Nezuko was staring at the stars with a strange focus while listening to him, trying to remember what he's saying.

“I'm not a big fan of the stars, but my old master made me learn about it, he said that a thunder breathing user should know the sky the sky as much as they know the blade.” Kaigaku said, making Nezuko stopping looking at the sky and instead now look at him.

“I know all about it for that reason, although I'm pretty sure if you ask Zenitsu he could barely tell you about five of them.” Kaigaku said, and fell into a silence after that.

Kaigaku isn't sure why he said those things to Nezuko, it's like he said he doesn't care about the stars much, but it felt like something he should tell her due to another reason.

But Kaigaku didn't kept his line of thought due to not wanting to show weakness to someone, especially a demon.

But with Nezuko's hand going towards his arm and tugging it almost like she can tell that Kaigaku is keeping something a secret, and he only changed to subject to Zenitsu to try and change the reason he's saying things.

“Fine I will tell you!” Kaigaku said, looking away from the sky and from Nezuko.

“If you keep going north following the stars, you will eventually find a house. It's a wonderful place, and also where I was told my parents once lived. It's where I was planning to live after turning 25, and leave the corp. But now I changed my mind about it.” Kaigaku said, with that the two fell into a silence.

With Kaigaku not going into the reason for his decision being changed, because it's not a noble reason or even out of admiration.

Kaigaku doesn't care about the demon slayer corps, he certainly dislikes the leader for being weak. There's only two reasons for him to have changed his mind.

The first is to show Yoriichi that he's with the correct person to inherit his legacy, and the second is even more personal and is the reason Kaigaku even talked to Nezuko about his change of mind.

But with those thoughts both Kaigaku and Nezuko fell asleep in the ground near eachother, it wasn't part of Kaigaku plan since he wanted to leave not long after he talked with Nezuko.