After setting the date, Hiru, Yukinashi, Aoba, and Rengoku Shinjuro all fell silent once more. Seeing that no one had anything further to report, Ubuyashiki announced the conclusion of the Hashira Meeting.
As previously agreed, Yoriichi left together with Hiru, following Ubuyashiki Kagaya.
After Ubuyashiki dismissed everyone else, Hiru first checked his pulse. Then, following the locations Yoriichi pointed out, he carefully cleared away the lingering effects of the Blood Demon Art within Ubuyashiki's body.
Once finished, he put away the cherry-blossom-colored stone with satisfaction and said,
"It seems Mikazuki has taken very good care of you. The Blood Demon Art inside you has only spread slightly over the past half year."
"That's all thanks to Hiru. Otherwise, I might still be unable to even identify what this is," Ubuyashiki said, shaking his head as he turned to Yoriichi.
"It seems the two of you have something you wish to discuss with me?"
"Indeed," Yoriichi nodded and removed his mask.
"But before that, I must first apologize to you. If I had not been careless back then, I could have slain Muzan at that time. None of the current troubles would have come to pass."
"You are being far too self-deprecating," Ubuyashiki said, meeting Yoriichi's gaze directly.
"Even from the written records that have been passed down, I can glimpse both the strength of Muzan Kibutsuji and the talent you possessed. Without you, aside from the Ubuyashiki family scrolls, we would know nothing of Muzan at all. You have no need to apologize."
"But—"
"There is no 'but.' Please acknowledge the power you possess," Ubuyashiki said, sitting upright.
"Though I did not witness the events of centuries past myself, there is one thing I can be certain of: without Mr. Yoriichi, there would be no Demon Slayer Corps today. Even setting aside everything else, the Breathing Styles you passed down alone have benefited us immeasurably."
"If there is anything that truly troubles me, it is the fact that the two of you are living on as demons, for reasons unknown."
Ubuyashiki rubbed his temple, looking rather pained.
"If it were Muzan, we could at least stake our lives on dragging him down with us. But when it comes to you… I cannot think of any solution at all."
"There's no need to worry about that," Yoriichi said, relieved to see no darkness in Ubuyashiki's expression.
"After slaying Muzan and my elder brother, Hiru and I will take the medicine that restores us to being human and live out our natural lifespans as ordinary people. Please be assured that neither of us has ever eaten humans."
"Only Hiru occasionally hunts animals and drinks their blood to maintain mobility and sanity."
Ubuyashiki froze.
"A medicine to return to being human? Was it developed by Hiru?"
Yoriichi glanced at Hiru with an amused look as he turned his head away.
"No. It was another friend. She was a healer who, centuries ago when I grievously wounded Muzan, broke free from her bonds and overcame her desire to eat humans."
"In fact, a prototype of the medicine was already created a hundred years ago. However, because my friend could not remain in prolonged contact with our blood, its effectiveness was insufficient. It was only within the past decade or so that it was truly perfected."
"Then if neither of you has taken it yourselves, how do you know it was successful?"
"We tested it," Hiru said, speaking up.
"We captured a demon under Muzan Kibutsuji's command. I transformed it, then had the transformed demon take the medicine."
"When it was first developed a hundred years ago, it could only revert demons without Blood Demon Arts. Now it can also revert demons with Blood Demon Arts. The time required and the dosage just differ depending on the demon's strength."
"I see," Ubuyashiki nodded.
"And what became of the demons who were turned back into humans?"
"After drawing blood samples for storage, I erased their memories and dumped them into the slums as vagrants," Hiru said, resting his cheek on his hand.
"They were all people-eaters, and not from this era to begin with. Sentencing them properly would have been difficult, so the most convenient solution was to leave them there."
Ubuyashiki let out a sigh of relief.
"That was likely the only option. So, what is it you wished to discuss with me?"
"It's about Muzan…"
Yoriichi and Hiru supplemented each other as they explained everything clearly to Ubuyashiki—from Hiru's encounter with Kokushibo, to Muzan, whose strength had inexplicably increased, setting his sights on devouring Hiru, and finally to how Muzan had uttered harsh threats only to retreat in the end.
"So that Kokushibo is the strongest demon under Muzan's command?"
Hiru nodded.
"I don't really want to admit it, but as far as I know, Kokushibo is a demon who possesses the ability to break free from bonds, and he's highly skilled in martial arts."
"If you really compare it, his relationship with Muzan is much like the relationship between my brother and me."
Ubuyashiki looked puzzled.
"Hiru means that Kokushibo—" Yoriichi began, then paused slightly when he received Hiru's dissatisfied glare.
"—that Kokushibo, like me, possesses the ability to break free from bonds and contend with the Demon King."
"Exactly. But Muzan's behavior has been far too abnormal to make sense of, which is why we wanted to hear your thoughts," Hiru said, looking at Ubuyashiki.
"Aside from the pharmacist-demon who helps us make the medicine, you're the only one we can discuss this with."
"Allow me some time to think," Ubuyashiki said, lowering his gaze as he organized his thoughts.
"Hiru first encountered Kokushibo and fought him."
"Yes. I was completely outmatched."
"If I calculate carefully, that period coincides with when the curse… the Blood Demon Art within me was strengthening," Ubuyashiki frowned.
"Could it be that something happened between Kokushibo and Muzan?"
"That shouldn't be the case," Yoriichi said softly, shaking his head with a troubled expression.
"The blood of the Primordial Demon remains within the body of any demon that is transformed. Even if they break free, that source blood does not disappear."
"It was precisely because of that source blood that I was able to sense Hiru's location and rush to him in time."
"And Kokushibo is someone who strictly adheres to etiquette and rules," Hiru added.
"If he truly betrayed Muzan Kibutsuji, then just like when he became a demon centuries ago, he should have first wiped out his family and then attacked the Demon Slayer Corps, seeing it through to the end."
"But Muzan is clearly still alive and well."
Ubuyashiki raised his head.
"I recall Hiru mentioning earlier that a demon's power comes from blood?"
"Yes, that's beyond doubt—my brother excepted," Hiru said, looking at Yoriichi with an expression that was difficult to describe.
"To be honest, I've never seen my brother consume any blood, and he shows no reaction to Rare Blood either."
"He was already free of desire when he was human, and it seems nothing changed after he became a demon."
Yoriichi merely reached out and gently ruffled Hiru's hair.
Ubuyashiki finally smiled, but the expression quickly turned serious again.
"Then how does a demon increase the blood within their body? I'm referring to the Primordial Demon."
"Through feeding, accumulation over time, and blood recycling," Hiru said, stroking his chin.
"I haven't tried the last method, though. After all, my brother is the only demon I've truly transformed."
"The others—whether for experimental cooperation or combat needs—ended up losing more blood than I could recover."
Ubuyashiki fell silent for a long while, his expression grave.
"Then… is it possible… that a demon could retain its source blood while offering the blood gained through feeding and accumulation to the Demon King?"