"I see."
Tomioka nodded slightly after hearing Takeo's account. "If it were Hiru, he would definitely have a way to save your brother. For now, I'll help you move first."
"Huh? Right now?"
"Based on what you said, that demon most likely came specifically for your family. There's no guarantee he won't come back." Tomioka lowered his gaze to Takeo. "I still have duties to attend to. I can't stay here guarding you indefinitely."
"Ah… then what about when Hiru and the others come back?" Nezuko looked uneasy. "What if they can't find us?"
This time, Tomioka fell into a brief, awkward silence before speaking. "I'll notify his Kasugai Crow. When the time comes, the crow will lead him to you."
Takeo and Nezuko exchanged a glance, then nodded. "Then I'll go pack our things."
"Yeah. I'll help."
...
As Tomioka began assisting the Kamado family with their move after understanding the situation, Hiru, on the other hand, was nursing a growing headache over Tanjiro's condition.
When Hiru first learned that Tanjiro had become a demon, he had anticipated two possible outcomes.
The first was that Tanjiro, with a ninety-nine percent likelihood, would be completely eroded by Muzan's blood, losing all rationality and degenerating into a beast driven purely by instinct.
In that case, Hiru could simply suppress him with the authority of the Primordial Demon, convert him into a demon under his command, and then have him cooperate with Tamayo to research a human-restoration medicine specifically for Tanjiro.
The second possibility was that Tanjiro would overcome the blood's influence against all odds, regain his reason, and willingly cooperate.
Hiru could then take him to Tamayo to develop the human-restoration medicine. That outcome would be ideal—and might even allow them to trace Muzan in reverse.
What Hiru never expected was for Tanjiro to end up in an even more complicated state—his sanity restored, yet his thinking entirely demonic, his consciousness fused together with a demon's instincts.
Despite having trained for a year in Sun Breathing and swordsmanship, Tanjiro was, at his core, still a boy who had never been tempered by real combat. If not for the sake of academic rigor, Hiru would not even have included "regaining sanity" among the possibilities.
After all, no matter how despicable or cowardly Muzan was, those traits stemmed from the psychological shadow left by his elder brother, Tsugikuni Yoriichi. Muzan's strength as the Demon King itself, however, was unquestionable.
Blood, as the embodiment of a demon's power, was also the most corrosive part of their existence.
For a human to be injected with such highly concentrated blood—forget surviving, merely not dying on the spot would already be considered exceptional.
Yet Tanjiro had not only absorbed that blood and transformed into a demon, he had also regained part of his sanity. This was precisely the situation Hiru least wanted to face.
It could only mean that Tanjiro's body was highly compatible with Muzan's blood, the two gradually merging into a state that was increasingly difficult to separate.
If Hiru wanted to convert Tanjiro into a demon under his own command, he would have to use his own blood to suppress and tear apart Muzan's blood. But in a state where the two were mutually absorbing and fusing, forcibly doing so would inevitably destroy the parts of Tanjiro's body already integrated with Muzan's blood.
Even if Tanjiro later returned to being human, those parts would never be restored—and worse, his physical functions could be permanently damaged.
If it were someone unimportant, Hiru would not care in the slightest. Loss would be loss, and he would not spare them a shred of emotion.
But Tanjiro…
Tanjiro was a descendant of Sumiyoshi. Sumiyoshi had been one of the very few people back then who truly acknowledged the brothers, and Hiru had always been grateful for that.
Because of this, he did not want to harm Sumiyoshi's descendants—just as he treated the Rengoku family with care.
That was why, even now, Hiru dared not forcibly convert Tanjiro into a demon under his command.
To be honest, if the timing were different, Hiru might even have praised the miracle—no, the divine intervention—that had occurred within Tanjiro, and then thoroughly dissected its underlying principles.
...
"Um… am I causing you trouble?"
Hiru snapped out of his thoughts and looked at Tanjiro. When his gaze met those clear, earnest eyes, he turned his head away irritably. "Yes. You're causing me a great deal of trouble."
Tanjiro did not understand what was troubling this fellow demon, but he still spoke instinctively. "Is there anything I can do to help?"
"What could you possibly do—no, wait." Hiru suddenly straightened. "There is something. First, you need to break free from the [Bond]."
"Bond?"
"Yes. The restraint the Primordial Demon places on subordinate demons. If you focus carefully, you should be able to sense it."
Tanjiro closed his eyes and concentrated, his voice full of uncertainty. "If I had to be more specific… what should it feel like?"
Hiru folded his arms. "How would I know? I've never experienced it myself."
Tanjiro opened his eyes and looked at Hiru. He didn't say anything, but his expression clearly said: If you've never experienced it, how do you know?
"Because my bond was broken," Hiru replied flatly. "I am the Primordial Demon." Watching Tanjiro's expression shift repeatedly, he twitched the corner of his mouth. "Stop making faces and do what I told you."
Tanjiro closed his eyes again and focused, but thoughts kept surfacing in his mind.
This fellow demon really makes things difficult… The information is way too vague. What exactly is this 'bond'? This feels even harder than when Father taught me breathing techniques…
Huh? Father teaching me breathing… I feel like, when my consciousness was hazy before, someone said something similar to me… What was it?
"Focus," Hiru said. "The 'Bond' is, at its core, the Primordial Demon's control over subordinate demons. If you concentrate, you can counter-invade his consciousness and sever your connection to him."
"Yes! I'll do my best!"
...
Hiru watched Tanjiro frown deeply in concentration, utterly bored. After a quiet sigh, his gaze drifted to the photo frame in Tanjiro's arms.
"I didn't expect you to carry something like that with you."
"Huh?" Tanjiro opened his eyes again and followed Hiru's gaze. He reached for the frame, looking confused. "I don't remember… ah?"
"Hey—why are you crying?"
"I… don't know." Tanjiro stared blankly as his tears slid along the cracks in the glass, seeping down and soaking the photograph inside. "I just suddenly feel so sad… This person feels familiar, but I can't remember them at all… This feeling is so strange… really strange…"
{Tanjiro, no matter what happens, never forget to breathe.}
"I… have to breathe."
In that instant, Tanjiro's pupils narrowed into thin vertical slits. The crimson mark at his temple spread rapidly, creeping across the left side of his face and showing signs of expanding even further.
A violent burning sensation surged through his internal organs once more. This time, however, Tanjiro did not stop because of the pain.
Instead, he focused all his attention on the searing heat coursing through his body, and the parts of his memory that should have been forgotten began to sharpen and return.
To an outside observer, however, Tanjiro looked completely unhinged—his gaze ferocious, his expression twisted, a low, animalistic growl rumbling from his throat.
...
Seeing this, Hiru immediately rose to stop him, only to be pulled back just as he was about to make contact.
"Don't go."
Hiru froze, then gradually relaxed. Turning his head, he looked at the figure who had arrived without a sound.
"Brother?"
Yoriichi withdrew his hand and gazed toward Tanjiro.
"Opportunities to touch the restraints are rare. Wait a little longer."
"Is that so…" Hiru paused, rubbing his chin as his gaze shifted to Tanjiro. "I only mentioned it in passing… This child is remarkably gifted."
"Indeed. I noticed it when I was guiding him earlier. Though he learns slowly, once he grasps something, he immediately applies it. Tanjiro is undoubtedly a prodigy."
"Or perhaps generations of practicing Sun Breathing altered their constitution?" Hiru crossed his arms and shook his head. "Did you go to the mountain, brother? How are this child's family?"
"Yes, I've already been there. Only destroyed houses remained—no one was found. Judging by the traces, it seems Swordsmen who received the message went to help them evacuate…" After briefly mentioning this, Yoriichi fell silent. "Was both of these incidents done by Muzan?"
"This time, yes. But I'm still uncertain about the Mikazuki matter… Still, blaming it on him directly is fine, regardless of who actually did it. Given our mortal enmity, he could certainly use a little more hatred piled on him." Hiru frowned slightly, changing the subject. "But you got here pretty fast this time, bro… Could there be other dangers around here?"
"No. Yuichiro and Muichiro were on a mission in the neighboring town, and since you happened to be nearby, I thought I'd come along to protect them and check on you. I just didn't expect…"
Yoriichi let out a long sigh. "Muzan and I always seem to miss each other."
"Not for much longer," Hiru looked at Tanjiro. "If this child can overcome the sunlight in one go, Muzan will likely go mad immediately, right?"
Yoriichi froze, then his tone carried a hint of reproach. "Setting aside how Tanjiro should overcome the sunlight, Hiru, are you suggesting using such a young child as bait?"
"Didn't you overcome it too, brother?" Hiru waved her hand, dismissing Yoriichi's implication. "Besides, how could I possibly use Sumiyoshi's descendant as bait? In this situation, I'd definitely put the pressure on Tamayo—get Tamayo to develop the human-transforming medicine for this child as quickly as possible."
Yoriichi relaxed. "How could I overcome sunlight? The fact I can walk in it now is all thanks to Hiru."
"Hey… Brother, you haven't forgotten that time when you forgot I was a demon and tried practicing your Breathing Styles, nearly burning yourself to death, have you?"
Yoriichi: Ah… That did happen.
"More than that…" Hiru sighed, her brows furrowing deeper as she examined the burn marks appearing on Tanjiro's skin. "Are we really just going to leave this child like this?"
"It's fine. His vital signs are stable. If anything goes wrong, I'll intervene immediately."
"Alright, then all we can do now is wait."
...
[Breathe. Keep breathing. It hurts so much… My body feels like it's on fire…]
The intense burning sensation accompanying each breath made Tanjiro want to give up instantly. Yet, a voice seemed to echo within him—just hold on a little longer. Just a little longer.
[Why am I doing this?]
[What am I doing this for?]
[How much longer must I endure?]
Question after question surged through Tanjiro's mind, yet he refused to stop breathing. As the burning grew more intense, different scenes began to appear before his eyes.
First came a space where countless rooms intertwined—a fantastical scene that greatly distracted Tanjiro. But before he could see more, his perspective shifted. A paper sliding door before him abruptly opened, revealing a familiar wooden hut beyond.
Tanjiro saw himself smashing the door of the hut, and then… saw himself?
[Huh? Why am I there? Is that… the [food] from earlier? No, am I protecting them? Why? Why am I protecting them?]
Tanjiro watched himself fighting desperately to protect those [food], and his confusion only deepened.
[Wait, what am I doing? Why am I attacking myself? Stop this!]
Watching himself get knocked flying by his own self, then grabbed by the throat and lifted up, Tanjiro's panic instantly reached its peak. He sensed something terrible would happen if this continued.
Tanjiro saw crimson Slayer Marks crawl up his left cheek. He saw himself gripping his own arm, demanding to know what he thought life was.
Yet in the next instant, Tanjiro realized the version of himself being held aloft by [Himself] overlapped with another figure.
[That's… Yoriichi? Ah, right. I was taught the Breathing Styles by Yoriichi and Father. But why? Yoriichi was such a gentle person. Why… is he so angry?]
{Give it to me! Stop!!}
Tanjiro saw the previously odd-acting fellow clutching his own corpse in utter disbelief, radiating a terrifying aura as he glared at [himself] with pure hatred.
While [he] conversed with that fellow, Tanjiro caught a glimpse out of the corner of his eye of the boy he had once called [food] cautiously peering through the ruined wall of the house, his face filled with worry.
[Why are you so worried? You're just "food" to me. Why fret over me?]
Before he could process it further, the scene shifted again. [Himself] returned to the jumbled space he'd first seen, and the memory abruptly ended. Yet in that instant, Tanjiro finally understood who this [Himself] he was now.
[Ah… So that's it. This "me" is the enemy. I was turned into a demon by this person. Those who eat—no, those people are the family I've always wanted to protect… Thank goodness. Thank goodness I was stopped before I could harm them…]
The searing pain in his body hadn't lessened one bit, but Tanjiro no longer feared this burning sensation. He knew there was something he had to do now.
Tanjiro's Breathing Styles reached their peak in that moment.
Crimson flames erupted from his body, consuming the tears at his eyes and the bloodstains on his skin. Though radiating an astonishing heat, the flames strangely soothed his burns.
As they rose and burned, they continuously drew out wisps of black smoke from within him.
At that very instant, Muzan, who had long since returned to the Infinity Castle and was savoring the Rare Blood meticulously selected and offered by his subordinates, suddenly crushed the cup holding the precious liquid in his hand.
He had clearly sensed that, just moments ago, another demon had broken free from his bonds—following Kokushibo.