Chapter Text
Disclaimer: Kimetsu no Yaiba (Demon Slayer) does not belong to me. All credit goes to Gotogue Koyoharu for their fantastic work, and Ufotable for their phenomenal interpretation of the manga into the groundbreaking anime series it is today.
This fic will also be semi-AU. It will be following canon events and facts, but only as a framework. As we’ll find out, some stuff has happened in between canon arcs, so the war lasted longer than it did in the original story. Also, I’ll be taking creative liberties with the world so yes, some things might not perfectly fit in with canon lore and rules.
Warnings: Mentions of canon character deaths; canon level violence, gore and mutilation; physical child abuse; negligence; mentions of alcoholism, depression and PTSD. Coarse language. Other mature themes.
Also, manga spoilers (especially if you haven’t read the manga until the end).
The year is 1910. Ten years after the fall of Kibitsuji Muzan.
The demons born of his blood should have died, in body and in mind, after the last of their master was burned away by the sun. But, contrary to what was once believed, the eradication was not complete. There are those who, for reasons unclear, managed to survive and continue being lurking, bloodthirsty terrors in the night.
For this reason, although most of its non-combatant members have been designated to other roles fit for the changing times, a small branch of the Demon Slayer Corps, under the leadership of the Ubuyashiki family, still remains. At the core of this fighting force, holding their ranks together, were swordfighters of magnificent skill and indomitable will. The cornerstones upon which Ubuyashiki Kiriya built the new generation of Demon Slayer Corps upon.
Seven slayers. Seven Hashira.
Sun. Water. Wind. Thunder. Beast. Flower. And...
In the cold darkness was a dance of glowing fire and scattering red.
Multitudes of crimson ribbons sprang from the dry earth, blooming in a twirl, twisting with deadly grace as they sought for blood and flesh.
But their prey will not come easy.
The deadly ribbons were shredded before they could fully descend on their target, as his blade slashed and stabbed through the lot of them coming his way. His movements made his blade gleam in the night in a gradient of white and orange flashes, as he jumped and weaved through the slashing whips and cutting through what he could not dodge.
I can’t let these things touch me. He chanted in his mind as he dashed forward, tightening his grip on his sword. I can’t let that demon cut me any more than she already has.
The aforementioned demon sat cross legged several feet away. She appeared to be a lithe, young woman dressed in a simple white and red shrine maiden hakama, with an oval face the color of pale porcelain that glowed against the moonlight, and long, silky hair that trailed rivers of of blood and ebony on the cracked earth. Her hooded eyes gleamed a sinister gold, illuminated by the glowing crimson and mauve, elaborately drawn pentagram she was in the middle of.
“Struggle all you want, but you will not be able to stop me. You are weeks too late!” She sneered as a number of ribbons twisted, coming together to form snake heads with sharp fangs and snapping jaws that came hurtling towards him.
He paused briefly, pulling a handful of kunai from his pouch. He let out a breath before throwing them, turning the kunai into volleys of light. The crimson dragon heads were torn off their neck, disintegrating midair as he ran past them.
The demon waved her hand again, directing more crimson ribbons to attack. “So foolishly stubborn! The ritual is already halfway complete! You persist only to die!”
Perhaps. He had to concede that possibility. The demon before him was not exactly the strongest he had ever faced—not by a longshot—but her blood demon art’s ability to make things difficult was on par with a lower rank Upper Moon’s. A demon art that messed with not just the mind, but a facet of reality itself.
No wonder so many of his fellow slayers have fallen to this demon, with the only survivor left so mentally incapacitated that he could not even take care of himself.
The memory of that poor comrade, and of the poor children who met their untimely end because of this monster’s harebrained scheme, sent fire coursing through his spirit.
I will not let their deaths, and my comrades’ sacrifices be for nothing.
“Even if it costs me my life, demon, I will stop you.” He growled, tightening his grip on his sword. “Whatever the cost, I will not allow you to succeed.”
“Such poor conduct.” The lady tutted, twirling a few strand of her long ebony tipped crimson hair. “My name is Higabana, not demon. I’m fairly certain you have not forgotten that, at least.”
He glared and said nothing.
Higabana’s sigh sounded long-suffering as more crimson ribbons emerged from the ground around her. “What a waste of time. Soon, you, along with this world, will cease to even be a memory. But if you insist, then come, and I will show you hell.” She tilted her head forward, her fanged sneer gleaming mockingly at him. “Hashira-boy.”
No matter what it takes. Clenching his jaw in determination, Rengoku Senjurou braced his feet on the ground, his embroidered haori fluttering behind him.
I cannot allow her to succeed in bringing Kibitsuji Muzan back to life!
“Good evening, oyakata-sama.”
From his seat at the far end of the receiving room, Kiriya Ubuyashiki smiled to Senjurou in greeting. “Good evening, Rengoku-san. I trust you are in good health?”
“I am well, thank you.” Senjurou answered, setting himself down to a seiza before his young lord, his nichirin blade by his side. “How may I be of service?”
Kiriya slid a small stack of papers to him. “There have been several concerning reports from the Aichi prefecture. As you are well-traveled, I believe you have heard of them?”
Senjurou flipped through the file, his frown deepening the further he went. Staring back at him from the pages were the faces of at least forty children ages four years old and above, all who have reportedly gone missing within a span of several months. “These are...the missing children who disappeared around Nagoya. I have heard of them, but I had no idea they were this many.” He met Kiriya’s gaze. “You suspect a demon is involved?”
The young lord nodded. “There is no concrete evidence, but I have reason to believe so. The fact that these children have disappeared without a trace is odd enough, but the missing persons reports about them have a certain, unusual commonality.”
“And that is?”
Kiriya frowned thoughtfully. “No one seemed to recall the children’s last known whereabouts, as if they literally disappeared right under their guardians’ noses. Witnesses not being able to remember where they have last seen the children or what they have been doing prior to disappearances is a common theme in all the reports.”
Senjurou hummed in contemplation. That was unusual, and too specific a situation to be present in all of the incidents. “So, a mind manipulation blood demon art, like Tamayo-san’s?”
“Most likely, as some of our slayers have found out.”
Senjurou had expected it, that an initial force of slayers would be sent first. As was protocol, depending on the difficulty of a mission, lower ranking slayers were usually deployed first as a way for them to gain experience and raise their standing in the organization.
But, from the way the young master spoke lowly, it obviously had not turned out well. “I have initially sent four of our Tsuchinoto to investigate two weeks ago. Only one of them have returned, but...” Kiriya’s lips thinned. “His mind was broken, to the point that he no longer remembers who he is or even how to function as a normal human being.”
Senjurou sucked in a breath. How cruel! A physical death, no matter how excruciating, is certainly much more merciful than completely losing one's identity! “And how is he now?”
“He is currently in rehabilitation. Our utmost priority for him is to help him remember how to take care of himself, and hopefully reclaim some, if not all, of his memories.” The Ubuyashiki head answered. “However, the problem about the perpetrator still remains. I understand that you have just come back from your previous mission from Edo, but this matter is quite urgent and you are the only Hashira currently available.”
Senjurou shook his head. “Please do not worry, oyakata-sama. It is my honor to help however I can. And I agree, whether or not there is a demon involved, this matter must be resolved quickly as possible. We cannot let any more children fall victim to this.”
Kiriya paused. “Do you intend to leave immediately? I did say that this was an urgent matter, but considering the danger, it would be best if you have another Hashira with you.”
That would be ideal, Senjurou knew, but in truth, they were already stretched thin as it was. Instead of the traditional nine, the number of active Hashira dwindled to five. While the Wind and Water Hashiras were allowed to retain their posts, it was an unspoken agreement among them that, given their extensive injuries after the war with Muzan, those two are technically retired in all but name. Kiriya himself had decided that they, as well as the former Sound Hashira, are only to be summoned during direst of needs.
That meant that, other than the Flower Hashira, they all had to take twice as much territory as their predecessors in order to cover the whole of Japan. The Ubuyashiki family’s resources and their allies have made doing so easier, but it was still hard work to keep an eye on their assigned areas, on top of the missions that they will get from time to time because of an occasional demon of at least Lower Moon difficulty will show up every now and then.
I can’t add to their burdens. Senjurou decided. I have to do it. I have to be enough...
“I don’t have the luxury of remaining weak anymore, Tanjirou-san.”
“Be at ease, oyakata-sama,” Senjurou shifted into a kneeling position and clenching his fists over the tatami flooring. “I will depart immediately, and I will find whoever is responsible for these disappearances and the injuries of my fellow slayers.”
“Rengoku-san.”
“My fellow Hashira are still currently occupied, and I would not wish to divert them from their duties if I can help it. Please leave this to me. I will do my utmost to not fail you or the Demon Slayer Corps.”
There was a moment of silence that seemed to stretch for ages, save for the sound of running water and the sound of bamboo hitting stone.
Then Kiriya’s expression softened.
“Your heart burns with the Flame of your house, Rengoku-san.”
Senjurou blinked, bemused. That was not been one of the reactions he had been expecting. “Eh?”
“You are one of the five Hashira—the youngest among them—forged in the fires of our war against Kibitsuji Muzan himself. We have all seen how hard you have worked, how you have taken the Breath and stretched it to its limits to make it your own. No one here doubts your ability as Hashira.”
“I...” Senjurou swallowed the returning lump in his throat. “Thank you, oyakata-sama.”
It wasn’t that he doubted Kiriya’s sincerity. Really, the teen, despite being years younger than him, had proven himself to be a very capable leader, growing to be as wise and as compassionate as his father before him. Yet Senjurou always felt that the young master (and many others) thought too highly of him. The only reason he even reached his rank was because there frankly wasn’t anyone in the Corps who could barely match up to the new generation Hashira.
But before he could reflect on that train of thought, Kiriya went on. “However, I sense that this perpetrator is far more dangerous than they appear. Regretfully, I cannot see it clearly, but there is the sense of foreboding, that this confrontation will be the start of something.”
Senjurou inhaled sharply. “Something similar to Muzan?”
Kiriya’s frown deepened. “In truth? Potentially so. I have no means of knowing for certain how dangerous your target is, other than the theory that its abilities have something to do with influencing the mind. I am not saying that they are beyond your capabilities to handle, but I urge you to exercise caution, Rengoku-san. I will leave it to you should you wish to pursue this mission alone, but do not hesitate to send for assistance should it be required.” Kiriya paused for a breath. “You and your fellow Hashira are vital now, more than ever. It would be a devastating blow to us to lose any of you.”
The thought made Senjurou frown. This is supposed to be a time when the power of the Hashiras should be barely needed. Muzan is gone. All that remain are his fear mongering remnants and...those poor souls who they have managed to corrupt beyond saving.
But so far, Kiriya hadn’t made them out to be a threat akin to the demon progenitor’s level. A danger that required the Demon Corps to have as much Hashira-level slayers as possible.
Or perhaps the young Ubuyashiki head had seen more than he was letting on?
The young Rengoku shoved the traitorous thought aside. The young master didn’t need to share any more than he thought necessary. His judgment had done the Demon Slayer Corps well these last ten years.
Senjurou was not going to start doubting him now.
“Argh!”
A small grin tugged at Senjurou’s lips, in spite of having been flung all the way to the opposite side of the room. The smirk had gone from Higabana’s face, replaced by open-mouthed indignation at the lacerations he tore at her torso and limbs.
“You!” She snarled, breathing heavily from the effort and the pain. “To think...a weak boy like you...would have that blade! That mark!”
“I’m a Hashira, demon. It’s your own fault for thinking that I am only one in name,” said Senjurou, forcing down a wince in favor of a triumphant smile. “How does it feel to get cut by a bright red Nichirin blade?”
She only glared in response, but he didn’t need her to say anything.
Her wounds haven't even begun to close yet. It will definitely take her a while to heal them, on top of regenerating the arms I just cut off. The constant attacks, the ritual and the bright red nichirin blade, the odds are stacking steadily against her now.
But while he had done considerable damage to the demon, Senjurou himself wasn’t faring better. His own upper torso was littered with slashes, with an especially long one cutting from his left shoulder down to the opposite side of his waist. There was also a deep cut on his right cheek, and a gash on his left eye that forced it to stay closed.
Definitely beyond saving, just like Aniue’s. At least we'll make a good pair, right? Like Tanjirou-san and Kanao-san. Senjurou’s chuckle turned into a wince at the thought of how kindhearted Tanjirou would react to this. Tanjirou had always worried about him more compared to the others.
Ah, Tanjirou-san, Yushiro-san, Oyakata-sama, I’m sorry. It looks like I’ll have to break my promise. I don’t think I’ll last long with these injuries and with her blood demon art. Senjurou let out a hacking cough that tasted like iron. But at the very least, I have to stop her. This way, no other slayers have to die. No other children have to be sacrificed. No one else has to get hurt...
“This...this is nothing!” Higabana grit her teeth before taking in a deep breath. Senjurou tensed when he saw her glow a sickly crimson and black light, and the crimson whips around her began to dissolve into columns of bloody kanji.
The young slayer gasped. No! It can’t be!
“It...doesn’t matter, what happens to this body!” Higabana continued. “I will not need it, where I’m going!”
She raised her arm stumps to the air, looking up to the ceiling where the a new gathering of bloody kanji trails bloomed. Her face, a twisted portrait of the agony and bliss of madness. “Just a little more. A little more, and I will change your fate! I will be the one who will save you and bring this mundane world to its knees! Muzan-sama!”
“I WON’T LET YOU!” Senjurou forced himself to this feet, bracing his legs into a charging stance.
“DON’T GET IN MY WAY, HASHIRA-BOY!” Higabana continued to scream, even as the effort forced blood out of her throat, cascading down her pale neck like a waterfall. “Blood Demon Art: Grave of the Forgotten!”
Twisters of red tendrils came from the ground like bamboo shoots, unfurling into deadly spinning petals to block his path. They were plentiful and dangerous, but they also remained stationary.
It’s a last stand. She doesn’t have enough energy left to sustain the ritual and to attack me at the same time, so she needs to stay on the defensive. All to buy her time. Senjurou thought. Time which her time manipulation blood art cannot give her.
But, God, is her blood demon art a pain. Time AND memory manipulation, really, how unfair is that? It was why Senjurou was having a much harder time than he should have with a demon of her caliber. Every slash of her red whips would either affect his speed and reaction time, or would cause him to forget a variety of things, from his breathing techniques to even the most basic dodging maneuvers.
At this point, with how many times he had been cut up, Senjurou had forgotten all but three of his most powerful breath techniques. It was a crushing thought, the underlying implication that he may have lost the fruits of years of sweat, blood and tears in mere seconds.
All that it took to turn him into the slayer that he is today. Wiped from his mind, possibly forever, as if they never existed...
He took a large breath of air.
Don’t give up. Senjurou chanted in his mind. He could swear the mantra spoke in Tanjirou's voice. Don’t ever give up. No matter how hard it gets. No matter how much it hurts.
Because if he fell here, and Higabana’s ritual somehow succeeded, then everything the Demon Slayer Corps had fought for—everything his predecessors and peers had died for—would be wasted. Everything they have sacrificed for a peaceful future without demons will be undone.
Don’t give up. Don’t give up. He felt the heat of his technique expand his lungs and course through his veins like molten lava as he tightened one of his hands on his sword’s hilt. The other slid though his glowing red blade, as if sending the fire in his body into the metal through his fingers.
There was a sensation on his back, like gentle hands keeping him upright, ready to push him forward. It might have been his imagination, but it gave him strength.
Flames erupted from beneath him as whole body shone, a radiant blend of white and orange.
Chichiue, Hahaue, Aniue, please give me strength.
The warmth like hands on his back spurred him forward like wings.
"Star Breathing, Ninth Form!"
“You want to leave? Now?”
“The sooner, the better.” Senjurou nodded at Yushiro’s inquiry. “There’s no doubt about it now. The one behind the disappearances of those children is definitely a demon.”
"Obviously. You don’t need five days of reconnaissance work to tell ME that." The pale demon thumped his index finger on his desk with visible agitation. "What I want to know is that why are you in such a rush! Kamado just sent word that he is on his way.”
Senjurou shook his head. “As much as I will appreciate Tanjirou-san’s support, it will take him another day to get here.”
“Which wouldn’t be the case if he still had the talismans I have given him! Seriously, what kind of idiot loses ALL of them in one go?!” Yushiro grumbled lowly under his breath, making Senjurou laugh uneasily. “But that still does not answer my question, Rengoku. Or are you that eager to end up like the last slayer who came her way? The fool could barely remember how to breathe when we first found him.”
Years of working with Yushiro helped Senjurou develop a keen sense of understanding of the demon. While still as abrasive and blunt as ever, Yushiro had established himself as one of the Demon Slayer Corps’ most reliable allies. And, to the veterans of the war with Muzan, someone they can even call a friend. The acrid words and berating over perceived stupidity were just his ways of showing his concern, as Tanjirou and Nezuko both said.
(S omething Yushiro denied loudly enough to rouse all of Japan when the siblings said so in the demon's hearing range.)
Either way, Senjurou had become so used to him that the admonishment was taken in stride. “You know why, Yushiro-san. You helped me interpret what the writings in her previous haunts meant. You agreed that they were dangerous.”
It took several days of investigation as soon as Senjurou reached Nagoya for him to find out this much. Combining his and Yushiro’s notes with the information the Ubuyashikis had found, he managed to create an acceptable dossier of the demon behind the children’s disappearances.
“One of the few demons who had been turned shortly before the final fight with Muzan. First reportedly spotted in Nara. Prefers to eat women and children, but lately has been targeting the latter.” Senjurou had read out to his companion only yesterday. “Increased sightings and increased aggressive behavior in the last two months. Last seen here in Nagoya. Suspected to be responsible for the disappearances of forty four children in this area alone. Known blood demon art ability effects include memory and cognition manipulation. Although time manipulation can also be considered.”
Yushiro grunted over his crossed arms. “We don’t know for sure if she has such abilities.”
“Better to think that she does. Besides, there is just too much material, many of which were written in her own blood, that imply time manipulation abilities for us to ignore.”
"But they were all on time travel! Time travel, foolish Rengoku!” Yushiro pointed out with a long suffering sigh. “Such a thing happening is highly improbable, even by demon blood art standards!”
“But if it were?"
"Didn't you hear what I just said?"
Senjurou sighed. "Just humor me."
“At the one in a million chance that it is?” Yushiro’s sneer dropped on seeing how serious Senjurou looked. “Fine, fine. If she does succeed, then it will depend on what she actually plans once she goes back in time. And how what she has planned can affect us.”
“And if it were something as crazy as to bring Muzan back to life?”
Yushiro grumbled after what felt like a long pause. “Then we are all royally fucked.”
Back in the present, the pale demon cleared his throat. “Yes, I did say that. I also remember saying that it is still very highly unlikely that her time travel plan will succeed. You also have to consider how her formidable her demon art is. You are risking a lot by going in alone, for that one in a million possibility.”
“But we cannot waste this opportunity, Yushiro-san,” argued Senjurou. “We already pinpointed her location. What if, by delaying, we will give her the chance to escape again? And what if it will take us longer to track her down? More children could be killed! And her one in a million chance to time travel could happen! She might even be able to bring Muzan back to life!”
“And you could be dead by the time Kamado arrives." Yushiro pointed out. "Or worse.”
Senjurou paused. “If that is what it will take to stop that demon, then I’m willing to risk it.”
The demon and human held gazes for a moment longer before the former growled in annoyance. “What is it with you slayers and your lack of self-preservation? Even with Kibitusji and the Twelve Kizuki gone, you still find ways to get yourselves killed!”
Senjurou smiled. “I apologize for worrying you, Yushiro-san.”
“WHO THE FUCK SAID I WAS WORRIED?!” The demon stood up and pulled out a slip of paper marked with ink and blood then struck the space in front of him with it. The tag remained floating in the air for a split second before it glowed and crumbled into red fragments. A black and red diagram took its place before the pair.
Senjurou hummed at the the blood and ink seal. “It’s a good thing that you have such a helpful blood demon art, Yushiro-san. Otherwise, it would have taken me days to even get here.”
“It’s not mine, I keep telling you!” Yushiro said. “All these years and I still don’t understand how I got that biwa demon’s abilities. I only killed her.” He paused. “A bloody struggle, but just that.”
“Does it matter? You’ve made it your own.” Senjurou pointed out, to which the smaller boy shrugged. “Might as well. It was getting in the way of my illusion blood demon art anyway.”
The pair fell silent for a while before Yushiro turned to Senjurou with a grave expression. “This seal will take you to her last known location. I’ll give the details to your crow so Kamado can head over there himself.” He handed the demon slayer another slip. “But if things start going over your head before he gets there, don’t be an idiot and get your ass back here. You have more use to us alive than dead.”
Senjurou nodded. “I understand.”
“And don’t lose this talisman! I swear, if you even think of becoming like those—!” The blonde and red haired man sweatdropped when he saw a vein pop on Yushiro’s forehead. “Why you made such rowdy, irresponsible fools Hashiras again is beyond me!”
“W—Well, they are very talented—”
“At the art of idiocy and being irresponsible? Oh, definitely!”
“...Anyway, I better go.” Senjurou bowed to the waist. “Thank you very much, Yushiro-san. Please give Chachamaru my regards.”
“Tell her yourself.” Yushiro snapped as Senjurou put his hand through Yushiro’s teleporting blood demon art. "Damn cat seems to like you and Kamado better than me anyway.”
That made Senjurou smile. I should get Cha-cham another bag of treats once this is over.
His world burst into bright white flames.
Higabana screamed in shock when Senjurou charged at her, seemingly in a blink of an eye, cutting through the red whip defenses she set up around them as if they were cotton threads, before Senjurou lodged his blade deep into her neck.
She continued to scream, even as his sword dug deeper into her flesh, sending blood splashing all over his front. His right eye saw red. His nose smelled metal. His mouth tasted rust. His whole being burned with pain and energy from the heat surging through his muscles and bones.
Don’t give up. Don’t give up. He pushed his burning blade forward with a roar. Don’t give up.
“GAH! ACK! AARGH!” Higabana choked and cried, her eyes shrinking in a display of terror as the red ribbons around her trashed in a desperate frenzy to get him away. But while each of them managed to cut him, they also disintegrated upon contact due to the intense heat of his still blazing breath technique.
Still, the demon's attack continued to cut him, causing crimson to spiral and burst from the lacerations that carved its way up his entire body.
He couldn’t tell where his blood ended and Higabana’s began anymore.
Don’t give up! Don’t give up!
“YOU—YOU LITTLE SON OF A BITCH!” Higabana’s screech sounded like breaking glass to his pounding ears now that his blade is three-fourths deep into her neck. “YOU STUPID MEDDLESOME BOY! THIS—YOU CAN’T—!”
“I am no...mere boy, demon.” The blonde and red haired Hashira hissed with a defiant smile. “I am...the Star Hashira...Rengoku Senjurou!”
There was a thick, wet sound, followed by a ring of metal as a head went flying into the air, followed by a spray of glistening blood.
Then, a whirlwind of crimson, and an explosion of white.
GLOSSARY:
- Kunai: Japanese throwing knives, traditionally used by ninjas.
- Hashira: Pillar
- Haori: Traditional jacket worn over kimonos.
- Oyakata-sama: Master
- -san: Honirific. Roughly translates to Mr./Ms.
- Seiza: traditional Japanese sitting position wherein one folds their legs and sits their bums on them.
- Aniue: Formal term for Older brother.
- Chichiue: Formal term for Father.
- Hahaue: Formal term for Mother.
OTHER NOTES:
- Higabana calls Senjurou “Hashira-boy.” In Japanese, the term “boy” (used as a loan word by the Japanese, said as “boh-ya”) is usually used mockingly, as if to say the man they are referring to is a boy pretending to be a grown up.
OMAKE:
[An Excerpt from the Revised Demon Slayer Corps Secret Fanbook]
Star Hashira Rengoku Senjurou
- Age: 24
- Height: 160 cm
- Weight: 57 kg
- Birthday: Unknown (he’s not telling)
- Likes: Yaki-imo (roasted Japanese sweet potato), calligraphy, reading
- Breathing style: Star Breathing (Main), Flame Breathing
The youngest Hashira who, while unable to fully master Flame Breathing, through grit and determination, developed his own breathing style derived from Flame Breathing and Sun Breathing techniques. While not the physically strongest, his speed is second only to the Thunder Hashira, and his flexibility, only to the Beast Hashira. He is also the only known high-ranking slayer who can use specialized long range weaponry with his breath style. Is very popular among female Demon Slayers and Kakushi, but doesn’t seem to know it. He always visits his brother’s grave before going on missions.
Stat Board
- Strength: 7/10
- Speed: 9.5/10
- Endurance: 8/10
- Intelligence: 9/10
- Charisma: 8/10
- Cinammon Roll-ness: 11/10