Chapter Text
Yukio was trailing Kamado and his friends since they left the Butterfly Mansion. They were assigned a mission on a train and cry of thunder over there looked like the only one who would know what that was.
“Give me your weapons. I'll get them on the train for you.” Yukio said.
The three boys each had different reactions. Kamado turned slowly to look at him, Boar head got in a fighting stance, and Thunder boy was currently crying of fright.
“Assassin? When did you get here?” Kamado asked.
“I've been trailing you. You won’t get on the train with your swords so I’ll get them on for you.” Yukio insisted once more.
The three gave him their weapons and he disappeared, becoming one with the shadows as he moved onto the train.
“Rengoku.” Yukio said in greeting.
“UMAI!” Rengoku shouted.
“I am going to leave these four swords with you. Give them back to the slayers that board this train. You will recognize one of them.” Yukio said and left to the top of the train, hiding his presence from the world. He felt trapped by his own responsibilities but knew he had to do them. But for now, he would relax on the train. It would not be long before he dozed off.
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Yukio woke up to the sound of a person speaking.
“That looks fun.” This voice said. “They’ve begun having happy dreams.” Yukio fully woke up and continued to hide his presence. The demon's eye said Lower One. “They’re sound asleep. They can no longer awaken.”
Yukio made a decision to watch this play out while following the demon. The demon may think they would have fun but in the end, the fun lies with Yukio. Yukio would wait for a few minutes before Tanjirou arrived.
“Oh, you're awake? Good morning.” Lower One said. “You should have stayed asleep.”
Tanjirou looked at the demon, realizing what rank he was.
“I was showing you such a good dream.” Lower One taunted. “You should thank me — I could’ve shown your family being slaughtered.” Then Lower One took it too far. “Next time, shall I show you your father coming back to life?”
Tanjirou was furious. And understandably so. This demon had just mocked the memory of this boy’s dead family. If Yukio didn’t believe that Tanjirou could take this demon, it would have been long dead by now.
“You can’t go stomping around in people's hearts!” Tanjirou exclaimed. “You won’t get away with this.”
The form of a dragon made of water appeared around Tanjirou as the demon stuck his hand out. Tanjirou rushed forward but the demon’s hand spoke?
“Go to sleeeep…”
Yukio fell unconscious. He knew he was asleep. He never dreams so why would he see a perfectly fine Nori in front of him. They had no scar, no blindness, and was completely fine.
“Finally awake, are you?” The dream Nori said.
“No. I'm not. This is a dream.” Yukio replied. He was going to stab this demon if he made him live his one fear. Thanatophobia.
Nori smiled. “That's right, silly. Since you are an assassin, you would know what you must do if caught, right?”
Yukio only nodded and then cut his neck. He was back on the train watching as Tanjirou also woke up and ran forward again, only to hear another “Sleeeeep…”
This time, everyone he knew and loved was in front of him. He was bound to a wall and so were his loved ones. He then watched as a fake version of him walked out and started to torture those he cared for.
“MMMPH!” Yukio tried to scream before realizing his mouth was sewed shut. He was forced to watch as the fake him tortured but not killing the ones he cares for most. They had their fingernails ripped off, their fingers cut off, whipped, electrocuted, bones broken, stabbed, tongues were cut off. The screams of pain were tearing Yukio apart. The one person who had not been touched was Nori and Yukio started to panic. He would not let this happen! He couldn’t!
Yukio started to pull harder against the restraints. It was too late because the fake Yukio started to press a blade against Nori’s skin even against the whimpers of “Yukio please!” Or “No… stop this!”
Suddenly screaming filled the air. It was Nori's scream. Their fingernails were being ripped off. Yukio had finally gotten the tape off his mouth as one restraint broke. Nori was still screaming in pain as the fake yukio went about the torture.
As the real Yukio broke the rest of the restraints, the fake Yukio had already moved on to breaking Nori’s fingers. There was a glass wall between Yukio and the other two. He started to punch it. With every punch though, one of Nori’s fingers broke.
After the fifth punch, the glass spiderwebbed and he punched it once more, shattering it. Yukio ran up to the fake Yukio and broke his neck. And then something that shattered Yukio’s heart happened.
“Please… kill me… I can’t live like this anymore…” Nori had just told Yukio to kill them. And Yukio’s body listened. He didn’t want to but his body knew this was a better choice. But he couldn’t look away as he cut Nori’s throat with the same blade that tortured them.
Yukio’s face was wet. He didn’t know what this feeling was or why it was there until his vision blurred. He was… crying? There was no time for that. Yukio took the blade in his hand and decapitated himself.
Yukio woke up furious. He saw that Tanjirou cut off this demon’s head. Yukio dashed forwards and grabbed said head.
The demon started screaming but Yukio didn't listen. He grabbed the head in one hand and started to squeeze it with all his force. Lower One’s head popped like a grape.
“Follow me, Kamado. That demon isn’t dead yet.” Yukio started walking to the front of the train. His voice was cold, his eyes dull. But anyone could see that he was furious. He had finally reached a moment where he was so infuriated, he was silent.
“Yukio… what…?” Tanjirou asked.
“It’s nothing that complicated, I just want to kill him.” Yukio said and walked on. It would not be long before he reached the area where the demon’s real body was. The two were surrounded by coal before Yukio closed his eyes. The Conductor tried to stab him but before he could grab his wrist, Tanjirou jumped in front and got stabbed in the abdomen. This was the final straw fow Yukio.
“Tell me if this hurts.” Yukio started slashing at the floor of the train exposing the first vertebrae of the demon's neck. “Assassination Breathing, fifth form: Silent Fury.” Yukio slashed hundreds of times in just under three seconds, cutting the Demon’s neck into a powder. Yukio was thrown into the air and away from the train with Tanjirou. The conductor was still trapped under the train.
“Yukio…” Tanjirou said. “Please… free him. He was controlled by Lower One.”
Yukio said nothing but walked over to the train and pushed it up just far enough for the conductor to move and get away. He was barely containing his panic earlier but now it was irresistible. He started having a panic attack. He was vaguely aware of a fist coming his way so he moved but just barely enough. Then a sword was blocking something from hitting Tanjirou. It seemed like a good seven minutes had passed before Yukio was finally able to snap out of his panic attack only to see Rengoku dying and Tanjirou throwing his sword.
“Ren… goku?” Yukio said, barely able to keep his composure.
Rengoku gave Yukio a smile and turned to Tanjirou.
“Please don’t cry so hard, your wound will open up and then I won’t have my victory.” Rengoku said, remaining calm knowing this was his end. “Now listen, I want you to visit house Rengoku, where I was born. There you will find the writings of the past Flame Hashira. My father read them but I didn’t… so I don't know what’s in them.” Rengoku paused before continuing. “They may contain records of the Hinokami Kagura you mentioned.”
“P… please… Rengoku… isn’t there any way to stop your bleeding? Can’t you use your breathing?” Tanjirou said, desperate for Rengoku to live.
“No. I’m going to die soon. But I have something to say, so listen. I want you to tell my little brother, Senjuro, to take the path that he thinks is right, to follow his heart. And to tell my father to take care of himself. And…” Rengoku took a breath. “Tanjirou, I believe in your little sister. I consider her a member of the Demon Slayer Corps. On the train, I saw her. She shed her blood to protect humans. If she risks her life to fight demons and protect humans, she’s a member of the Corps, no matter what anybody else says!”
Tanjirou started to cry more over this.
“Stand tall and be proud. No matter how unworthy you feel… Keep your heart burning, grit your teeth and move forward. If you curl up in a ball and just hide, time will pass you by. It will not stop for you while you wallow in grief. Don’t worry about my death. I’m a Hashira. It's my duty to shield you junior members. Any Hashira would do the same. We cannot allow… the young bloods to be plucked. Tanjirou. Boar-head boy. Blondie there. You all keep learning and growing. Someday you guys will become Hashira and become the pillars for the Demon Slayer Corps. That's what I believe. I believe in you.” Rengoku then turned to Yukio. “Will you take my Haori and give it to Ōkami for me? I suppose he will find more of a use for it than I.”
Rengoku then looked back at Tanjirou and his eyes opened in surprise. Yukio supposed he was seeing his mother. Rengoku gave the world a final smile and then he died. Yukio collected Rengoku’s Haori and gave his sword guard to Tanjirou. “Take this. Give it to his family. Senjuro will likely let you keep it, Sengoku won’t care.” Yukio then walked off into the woods. He was going to visit Ōkami.