Mount Akaiiwa lay far from the Butterfly Mansion. Traveling only by night, Yosuke flew for four days straight before finally arriving at his destination.
Akaiiwa was an ancient volcano—long dormant for thousands of years. Its once-majestic form had been worn down by time and weather, leaving behind only a fractured and eroded shell of a mountain.
At its summit stood the ruins of old buildings, relics from the days when the Demon Slayer Corps and the Ubuyashiki clan had taken refuge there.
When Yosuke arrived, he was startled to see someone already among the ruins.
"Kokushibo…" he murmured.
Kokushibo turned to face him.
"Well, well," Yosuke said coldly, "I didn't expect to find you here. So Muzan really is searching for the Divine Priest family."
Kokushibo's expression flickered with surprise. "You already know?"
The search for the Divine Priest clan was a secret mission—one known only to the Twelve Kizuki. For Yosuke to have discovered it on his own was unexpected, even for Kokushibo.
Yosuke's aura flared—his presence as a Demon King saturating the air, ready to strike at any moment.
Yet Kokushibo made no move to draw his blade. He stood perfectly still, devoid of hostility.
Something was off. The man before Yousuke was nothing like the Kokushibo he had fought before.
"Why don't you draw your sword?" Yosuke taunted. "Given up already?"
Kokushibo said nothing. Instead, he slowly took something from his robes—a small bamboo flute.
Yosuke's eyes narrowed. He recognized it instantly.
Tsugikuni Yoriichi's flute.
Summoning his blood, Yosuke formed a crimson sphere that sealed both of them inside, ensuring their words could not be overheard by Muzan.
"You must have something to say," Yosuke said evenly. "Speak freely here—Muzan won't hear us."
Finally, Kokushibo spoke. "You've already figured out why Kibutsuji Muzan is looking for the Divine Priest family, haven't you?"
Yosuke nodded. "My guess is that Muzan wants to use their bloodline to overcome his weakness to sunlight."
"That's right," Kokushibo confirmed. "That's his plan. Every Upper Moon has gone into hiding, all focused on finding the descendants of the Divine Priests."
There was no trace of reverence in his tone when he spoke Muzan's name. The lack of subservience made Yousuke uneasy.
What happened to him? he wondered. How could his personality have changed so completely?
Unable to suppress his curiosity, Yosuke asked, "Kokushibo… what happened to you?"
Kokushibo lifted the flute in his hand and gazed at it quietly. "I am no longer Kokushibo," he said. "I am Tsugikuni Michikatsu."
He spoke slowly, his voice almost wistful.
"During our battle, Nakime teleported me away. By sheer coincidence, I found Yoriichi's grave."
"There, I finally saw myself clearly. I spent my entire life chasing strength… only to realize that it was never what I truly desired. How ironic."
His words carried raw sincerity—but Yousuke remained wary. Kokushibo was Muzan's subordinate, after all. There was no telling whether this was genuine remorse or a calculated act meant to gain Yousuke's trust.
"I see," Yosuke said, probing carefully. "So what do you plan to do now?"
"Nothing," Kokushibo replied calmly. "Things will continue as they are. As long as the Divine Priest family exists, it's only a matter of time before Muzan finds them. And once he does—once he becomes the so-called ultimate being—it will all be too late."
Yosuke's eyes widened slightly. "Are you saying… you plan to act as Muzan's spy?"
"Not exactly." Kokushibo's tone remained flat. "I am still his subordinate—for now. That will remain true until the moment he finds the Divine Priests."
A chilling aura rolled off him, forcing Yosuke to ask, "And when Muzan finds them… what will you do?"
Kokushibo's expression hardened, his voice turning to ice. "I will slaughter the entire Divine Priest clan. I will shatter Muzan's dream of becoming a perfect being. After all… I've done it once before."
"Done it before?" Yousuke echoed, startled. "What do you mean?"
Kokushibo looked down at the flute again, his tone unchanging. "At Yoriichi's grave… a Blue Spider Lily bloomed."
"What?!" Yosuke's heart pounded. The mythical flower—missing for nearly a thousand years—had been found by him.
"Where is it now?!" Yosuke demanded. He couldn't tell if Kokushibo's words were truth or deception.
"The Blue Spider Lily remains at Yoriichi's grave," Kokushibo said. "But so much time has passed… it may have withered completely."
Then, with firm resolve, he added, "I won't let anyone claim it. Creatures like us—demons—should never have existed in this world."
Yosuke exhaled in relief. If Muzan had not yet obtained the flower, that was enough. Perhaps letting it wither was the best possible outcome.
Even so, he couldn't bring himself to trust Kokushibo completely. No one could say for certain what lay in his heart—or whether the Blue Spider Lily truly existed.
"Did you find any traces of the Divine Priests in the ruins here?" Yousuke asked.
Kokushibo produced a small scrap of paper and tossed it to him. "There was this."
Yosuke caught it and examined it closely. Only a single line was written:
'When the boundary between man and demon begins to blur, the gods shall descend with a new revelation. Then, the Divine Lord will walk the world, bearing the word of heaven.'
The cryptic words read like a riddle, leaving Yousuke momentarily at a loss.
"Will you tell this to Muzan?" he asked quietly.
"I will," Kokushibo replied. "And I'll help him find the Divine Priests as well. I've already said it—anyone or anything that could make demons impervious to sunlight, I will destroy without hesitation."
Kokushibo looked at Yosuke impassively. "Even if you kill me now, it won't change anything. The moment I die, my memories will flow back to Muzan. He'll learn the truth regardless."
Yosuke took a breath, then made an offer. "We've found a way to break Muzan's curse. The blood curse inside Nakime has already been removed. If you join us, we can free you too—and together, we can bring down Muzan."
But Kokushibo refused without hesitation. "I will not join you. I do not trust you, Ubuyashiki Yosuke. The only person I ever trusted is long dead. And if I could do it… I wouldn't hesitate to cut you down myself."
With that, he tore open the wall of Yosuke's blood barrier and began to walk away, utterly unafraid of being attacked from behind.
As he was about to leave, Yosuke called out one last time. "Kokushibo—when it's all over… what will you do then?"
Kokushibo paused. His voice, though cold, carried a faint warmth.
"I'll go find Yoriichi. That fool must still be waiting for me. As his elder brother… how could I possibly leave him to face eternity alone?"