"Rest assured. I now speak to you on behalf of fate. If you slay Yōsuke Ubuyashiki, fate will grant you immunity to sunlight — and you will also become fate's servant, like me: a Divine Master, bestowed with tremendous power."
Kibutsuji Muzan scoffed, "Ha. Do you take me for a fool? Kokushibo and Nezuko Kamado have already overcome sunlight. If I devour either of them, I will gain the same trait. And become a servant of fate? I have no interest in being a lackey."
The Divine Master shook his head. "You are truly greedy, Muzan. You do wish to kill Yōsuke Ubuyashiki yourself, don't you?"
Muzan remained unmoved and speculated, "Since you came to me, it means you want Yōsuke dead even more desperately than I do. I guess if I die, no one will be able to restrain Yōsuke anymore, and that so-called fate will continue to be in chaos. Am I right?"
The smile left the Divine Master's face—Muzan had guessed his intent. After a moment of thought he said, "If you succeed in killing Yōsuke Ubuyashiki, I will tell you the greatest secret of this world. That secret concerns the very essence of how this world operates. As Divine Master, it is my foremost duty to guard it."
"I'm not interested in secrets. I prefer tangible things," Muzan replied.
The Divine Master countered, "If you overcome the sun and become the ultimate lifeform you desire, what will you do?"
"I will kill everyone who defies me and make this world a place of only demons!"
"Conquer the world, then. You might take an interest in that secret after all. I can say no more for now—you are not yet qualified to know it. So, what will you choose?"
Muzan fell silent. The situation was entirely unfavorable. If things continued as they were, the future might well play out exactly as the Divine Master had shown him.
Although Kokushibo and Nezuko had overcome sunlight, Muzan could likewise gain that trait by devouring one of them. But both Kokushibo and Nezuko would be heavily guarded by the Demon Slayer Corps and Yōsuke Ubuyashiki. Stealing them would not be simple and would likely end in disaster.
Muzan, extraordinarily cautious by nature, did not want to take that risk. He had waited a thousand years; now that a path to overcoming sunlight had finally appeared, he did not want to fail at the last moment.
The optimal course now was to cooperate with the Divine Master—whose true strength remained unknown. If they could eliminate Yōsuke, Muzan was confident he could annihilate the remaining Demon Slayer forces. And the Divine Master's kotodama — his Word Spirit — was an ability Muzan coveted deeply.
"Then show some good faith," Muzan said. "I can't trust you completely. You might stab me in the back during the fight, so I need to guard against that possibility."
The Divine Master asked plainly, "What do you want?"
Muzan answered without pretense, "Either let me overcome sunlight now, or give me your kotodama ability."
"There is no way to make you overcome sunlight right now. Kokushibo and Nezuko succeeded because they possess the Divine Priest clan's blood within them; you do not, so that lineage means nothing to you. As for the kotodama, it stems from my soul. I can give you a portion of my soul so you temporarily possess the kotodama."
Muzan, surprised, asked, "Soul? Does such a thing truly exist in this world?"
He recalled how Kokushibo had suddenly acquired Sun Breathing — clearly not from his own original power — and the Divine Master's mention of a soul made Muzan wonder whether Yoriichi's spirit had aided him that day.
"That concerns the nature of how the world functions; I cannot explain it in detail. But I can tell you plainly: souls exist, and so does the fabled hell. Now I will give you part of my soul."
The Divine Master extended his right hand, using his palm like a blade to plunge into his own chest.
Muzan was bewildered — must one harm oneself to extract a soul?
Strangely, even though the Divine Master's entire palm sank into his chest, no blood oozed out.
Slowly he withdrew his hand, and a pulsing, pure white orb of light hovered in his palm.
The Divine Master looked a little pale as he said to Muzan, "This is part of my soul. Swallow it and you will have my kotodama ability."
Muzan took the orb from the Divine Master and popped it into his mouth, swallowing it whole.
A pure white radiance suffused Muzan's body; he felt an endless power welling up inside.
"Kotodama — Force!"
Muzan immediately tried to use the kotodama he had just obtained, but the vision of the Divine Master crushing him beneath a gravity he could not overcome did not appear.
"What's this? Are you deceiving me?!" Muzan barked.
The Divine Master said coldly, "Your kotodama is ineffective against me. One more thing you should know: my soul now resides within you."
Only then did Muzan realize he had been tricked. "You lured me in so I would ask for the kotodama, then you intended to manipulate me!"
The Divine Master replied calmly, "Exactly. From the start I suppressed you with force. Someone as greedy and covetous as you would surely crave the kotodama. If I had offered it up front, you, naturally suspicious, would have refused. So I baited you step by step. Now I can grant you life or death at will."
Muzan — who had always been the one to grant life and death to others — found himself held in check by another. Rage boiled over and reason fled.
He immediately unleashed his Black Blood Briar upon the Divine Master.
The room filled at once with black, thorny brambles.
"Kotodama — Guard!"
At the Divine Master's command, a transparent dome formed around him. The black thorns could not breach the shield.
When Muzan tried to attack again, a pain originating from the soul tore through his body. He clutched his chest and collapsed.
The Divine Master walked to Muzan and looked down at him from above. "I told you: I can now give or take your life. The terms of our cooperation will not change. After you slay Yōsuke Ubuyashiki, I will give you whatever you desire."