After encountering Hiru, Kokushibo concealed himself nearby and settled in to wait for the final battle between brothers.
With each passing day, he found himself unable to stop revisiting his past, wondering how he had ended up here.
He lowered his gaze to the mark on his wrist and recalled what Hiru had said centuries ago, back when he was still human, at their father's funeral.
"I truly don't understand it Big Brother, you stayed by Father's side all that time and devoted yourself to him. Yet in the end, the last thing Father said to you was to find our elder brother… How ironic. Father never seemed to cherish what he had in the moment—only after losing it did he feel regret. It was that way with our elder brother, with Mother… and now with you."
"Watch your words. Children should not speak rashly of their parents."
"But Father didn't even remember me in his final words. Can I really be considered a member of the Tsugikuni Clan?"
...
"In any case, Big Brother, I also want our elder brother to come home. But I hope you won't deliberately search for him. Even if you find him, please don't force him to return."
"Why?"
"Because sometimes, not interfering with each other is the best state. If you become too fixated on someone or something, your own life can fall apart."
"I won't let things reach that point. Don't think too much."
"...Big Brother."
"Hm?"
"If one day you find something you truly wish to pursue, then leave everything to me. I'll follow your example and take care of it all. I don't know whether I'll earn recognition or whether I'll succeed—but if it's for you, I'll do my best."
"You're saying strange things again. I'm just preparing for the worst…"
Thinking of this, Kokushibo closed his eyes.
He could still clearly remember the unwilling resentment when Yoriichi saved him, the self-loathing when he saw Hiru willingly walk toward death during the clan's annihilation, the confusion when he later heard of their deaths, and centuries afterward—the shock of meeting them again, and the fury of being defeated by Yoriichi in a single move.
In every one of those moments, he had ended in disgrace.
He could not help but question himself.
He had abandoned everything in order to surpass that man. But after casting it all aside to become a demon—had he truly grown stronger?
Kokushibo no longer had an answer.
Now, aside from anticipating a decisive battle with Yoriichi, he did not know what else he sought. Or perhaps he was simply forcing himself to continue down this path, so that his past would not look like nothing more than a cruel joke.
"Eh—there's someone else in this area?"
At the sound of the voice, Kokushibo lifted his head and looked toward the cave entrance, where a boy stood bathed in moonlight.
"...Who?"
"Don't be alarmed! I'm a swordsman of the Demon Slayer Corps! Not anyone suspicious!" The boy stood at the mouth of the cave. "Judging by how you look, you're a samurai too, right? No wonder you're staying in the mountains… With the current sword ban, it must be inconvenient to move around in the city."
Kokushibo merely watched him from the shadows without speaking.
"But the mountains are dangerous too, you know? Didn't you hear that this whole area was sealed off a few days ago?"
"...Sealed off?"
"Yeah. It's because this mountain region is dangerous right now, and the person responsible for handling it can't get away. Come on, I'll take you out. Good thing I checked carefully. What if you'd run straight into danger?"
So this is how Hiru handled it. But this child…
Kokushibo rose and walked slowly toward the entrance, his gaze fixed on the boy.
"What is your name?"
"Ah, I didn't introduce myself. I'm Tokito Muichiro. And you—eh?"
Kokushibo lowered his eyes slightly. "What is it?"
"Huh? Um…" Tokito Muichiro looked up at him, confusion written across his face. "It's just… you seem kind of familiar."
"So that is your impression."
"Huh? What kind of tone is that? Uncle, you talk really strangely. Is it because you don't talk to people much? Is that why your tone sounds so odd?"
Kokushibo remained silent.
"Relax," Muichiro said, patting his arm lightly.
"Hiru says everyone has their own traits. You shouldn't look down on someone just because of a small flaw. I won't discriminate against you, Uncle. My brother always says I'm scatterbrained anyway."
Kokushibo's steps faltered. He turned his head slightly. "Hiru… big brother?"
"Yeah! Hiru big brother knows all kinds of things! He's my favorite person after my brother! Every time he comes back, he tells me different stories!"
"...Call me brother as well. Or call him uncle."
"What?" Muichiro frowned. "Uncle, you really are strange… Why would I call you brother? There's a huge age difference between us."
"Because Hiru is my younger brother. If you address him that way, the seniority is wrong." Kokushibo watched as Muichiro's expression visibly froze, his frown deepening. "And why are you calling him brother in the first place? That's absurd."
"Huh? Well… Hiru did tell us to call him uncle at first…" Muichiro looked up at him, one hand resting on the hilt of his sword. "But you're getting more and more suspicious. I've never heard of Hiru having any brother besides Yoriichi."
"Yoriichi is my twin younger brother." Kokushibo lowered his gaze and released a trace of his demonic aura. "And why do you think this area was sealed off?"
The instant he felt that presence, Muichiro drew his blade and leapt backward, eyes wide and alert.
"...You're a demon?"
Seeing Tokito Muichiro's pupils constrict and his body tense, Kokushibo fell silent for a moment before withdrawing his aura. He turned and walked back into the cave.
"Return. Tell Yoriichi to come to me as soon as possible. And do not let anyone from the Demon Slayer Corps disturb me."
Yet after a brief pause, Muichiro followed him again.
"I was wondering why you and Yoriichi look so alike… Are you really Hiru's older brother?"
Kokushibo glanced at the boy who had once again come close, frowning slightly, but he nodded.
"No wonder Hiru acted that way…" Muichiro trailed behind him without the slightest hint of fear. "Is this what they mean by being reminded of someone by a scene?"
Kokushibo turned his head. "...Reminded by a scene?"
"My friend's older brother was turned into a demon too. Hiru did everything he could to help him survive."
Muichiro looked up at Kokushibo, who had stopped walking. "It happened at the beginning of last month. Oyakata-sama's wife even personally invited my friend to join the Demon Slayer Corps as a witness… Didn't Yoriichi and Hiru come back to tell you?"
"...No. And they would not have told me."
"How could that be? They must have been too busy to come see you. Yoriichi has been investigating the recent frequent attacks on the Wisteria House, and Hiru has been traveling around capturing demons for the evaluations. Those are important matters."
Muichiro's expression was earnest.
"You're family. How could they possibly ignore you?"
"But this time, besides being busy, it's probably also because they're embarrassed, right? After all, the one who turned into a demon is Yoriichi's disciple… Yoriichi and Hiru must find it hard to bring that up, don't you think?"
Kokushibo was silent for a long time before he finally spoke.
"Is that so… Yoriichi found a disciple."
Muichiro failed to notice the unmistakable signal that Kokushibo wished to end the conversation. He remained as animated as ever.
"Yeah! He's really incredible. Even after becoming a demon, he never forgot that he wanted to protect his family. And he managed to suppress the urge to eat people—I seriously admire him!
"At first, we even fought because of a misunderstanding. He thought we were there to attack his family and gave off some terrifying hostility. But once we cleared things up, we trained together. His sword techniques are incredibly clean, and when he uses a Nichirin Blade, there's this crimson form like flames—it's unbelievably cool!
"If I could learn Yoriichi's Breathing Styles, I'd start training from scratch. I want to have that dazzling form when I swing my sword too…
"Oh, and my friend said his brother first learned his Breathing Styles from their father. Yoriichi only found him later, took him as a disciple, and corrected his techniques. Isn't that amazing? Total genius, right?"
Muichiro continued chattering on, completely unaware, brimming with excitement.
Kokushibo, however, tightened his grip on his sword hilt until his knuckles whitened. He could no longer hear the words clearly.
Look at this.
While he was still hesitating over his own choices, Yoriichi and Hiru had already left him far behind.
When everything came to an end, with Yoriichi's nature—call it detached or indifferent—if Hiru refused to die, Yoriichi would undoubtedly do everything in his power to persuade him.
Kokushibo could almost hear it.
"We are no longer of this world. Now that all karma has been settled, we should not remain."
And with Hiru's pliable temperament, even without persuasion, a single disappointed look from Yoriichi would be enough to sway him into obedience.
Yoriichi had passed down his martial skill. Hiru had left behind countless paintings. Even if they did not continue to exist as demons, their wills would live on.
But him?
After the final battle, what would he leave behind?
As a demon, once he died, not even a handful of ashes would remain.
Look at you. Whether as Tsugikuni Michikatsu or as Kokushibo, you accomplished nothing. A complete and utter failure.
"Um…"
"Hmm?"
Muichiro studied his expression carefully.
"Did I talk too much and make you angry, Big… Big Big Brother?"
Kokushibo: …What kind of disrespectful address is that?
"By the way, since Yoriichi and Hiru hid you here and let you live in this place… that means you've overcome the urge to eat people, right? And judging by how you dress, you're really skilled with a sword too."
Muichiro's eyes shone with admiration.
"So can I come here to train when I have time? Will you teach me, Big Big Brother?"
"I do not have the time."
"So cold! I wanted to talk more with you!"
Kokushibo's gaze remained distant.
"I am a demon. You are human. There is nothing to discuss. As a swordsman, your lack of vigilance warrants severe punishment."
"Ah, but you don't feel malicious," Muichiro said, kicking a small stone along the mountain path. "Yoriichi's aura-sensing has never been wrong. And since you're Yoriichi's older brother, that makes you one of my older brothers too. It's only natural for a younger brother to want to be close to his older brothers, isn't it?"
"Utter nonsense…" Kokushibo withdrew his gaze. "Go. Do not return."
"But I still want to—"
Before Muichiro could finish, Kokushibo's figure vanished.
After a brief pause of stunned silence, Muichiro's eyes lit up instead.
"So fast! No wonder he's Yoriichi's brother! I'm definitely going to get him to teach me swordsmanship! Hehe… this must be Yoriichi and Hiru's secret, right? Then I'll just tell my brother when I get back. We'll come train together!"
With renewed enthusiasm, Muichiro resumed his patrol.
From the shadows, Kokushibo watched the boy leave with a bright smile, a thousand emotions churning within him.
The moment he saw Muichiro, he had known.
The resonance of blood could not lie.
He was his descendant.
He is nothing like me, this failure. That is good. There is no need for me to interfere with them. Before my battle with Yoriichi, I should avoid creating further trouble.
And yet, Kokushibo had underestimated Muichiro's persistence.
Three days after that night's encounter, Muichiro returned—this time bringing a boy who looked exactly like him to Kokushibo's new dwelling.
"Seriously, Big Big Brother! Why did you suddenly move? I came the day before yesterday and missed you!"
Muichiro tugged the identical boy forward.
"This is my brother, Tokito Yuichiro. Just like you and Yoriichi, we're twins!"
Kokushibo looked at the two boys standing beneath the sunlight outside the cave, his expression unreadable.
"I told you. Do not return."
"Well, you don't have anything to do during the day anyway, right? Help us train!"
Muichiro beamed.
"Without Yoriichi and Hiru around, I only have my brother to spar with. Don't they say pressure leads to improvement? Help us out! You're a powerful swordsman too, aren't you?"
Kokushibo simply fell silent, already considering relocating again that very night.
While Muichiro continued pestering him with earnest insistence, Yuichiro stood to the side.
One hand restrained Muichiro from stepping into the cave. The other rested lightly on his sword hilt. His gaze carefully appraised Kokushibo—a man who bore at least a nine-tenths resemblance to Yoriichi.
The night before last, after completing his patrol and reporting to the Wisteria House, Muichiro had rushed over, speaking in a conspiratorial whisper about having discovered a tremendous secret.
He had recounted everything that happened during his patrol.
Yuichiro had not believed him.
Not until Muichiro insisted on combing through the mountains to find the person after failing once.
But now, seeing the man in person, Yuichiro felt a headache forming.
The figure before them had been suppressing his aura. Yet upon seeing the two of them, he had deliberately released it.
Having already worked within the Demon Slayer Corps, Yuichiro instantly recognized it.
Not human.
Combined with what Muichiro had told him earlier…
Yuichiro's lips twitched.
The Sun Hashira and the Human Hashira actually had an older brother who had become a demon.
With Tanjiro's matter having only just concluded, if this news were to spread now—
The Hashira would lose their minds.