The Infinity Castle was held in a state of rigid, agonizing tension. Muzan Kibutsuji was pacing the central platform, his movements sharp and predatory. He was in his aristocratic form, but the elegance of his suit was betrayed by the vein throbbing in his temple and the way his plum-red eyes burned with a cold, flickering fury. Below him, the Upper Moons were gathered in a semi-circle, their foreheads pressed to the wood. Kokushibo sat at the front, his three pairs of eyes fixed on the floor, his presence a pillar of silent, stoic endurance. He knew this mood. He had seen the Demon King in many states, but none were as tedious as when he began to dwell on his domestic frustrations.

"It is an insult," Muzan’s voice hissed, echoing through the impossible geometry of the halls. He stopped abruptly, gesturing sharply toward the shoji screens of the private upper chambers where you resided. "A thousand years. Ten centuries of my blood, my power, and my guidance. And yet, she still carries that... stench of humanity like a cheap perfume." He turned to Kokushibo, his eyes narrowing. "You, the First Moon. You understand the necessity of shedding the past. You abandoned your name, your family, your very mortality to reach the peak. But my wife? She still watches the seasons change with that pathetic, misty-eyed longing. I found her yesterday... staring at a cluster of dying wisteria as if it were a tragedy. A demon of her rank, higher than all of you, and she wastes her spirit on sentiment." Douma tilted his head, a playful, artificial smile touching his lips. "Perhaps she just has a very sensitive soul, Master? It’s quite charming, in a way! I find her mercy toward the lower ranks to be almost... poetic."

"It is not poetic, Douma! It is weakness!" Muzan roared, the floorboards beneath him splintering under the sheer force of his pressure. "She is the strongest creature I have ever created, a being who should be a god of carnage, and yet she refuses to devour more than she needs. She speaks to the humans as if they were peers. She remembers the songs of her childhood. It is a rot that refuses to clear." Kokushibo remained silent, though his thumb twitched against the hilt of his sword. He respected your power—it was undeniable—but even he found your lingering humanity to be a baffling enigma. "I have tried to purge it from her," Muzan continued, his voice dropping to a dangerous, low vibrate. "I have shown her the futility of the human heart a million times over. But she clings to it. She looks at me with those eyes... those soft, unforgiving eyes... and I see the girl I took from that village a millennium ago. It makes her fragile. It makes her a liability."

He looked up at the ceiling, his expression a mask of frustrated possessiveness. "She is ranked above you all, yet in her heart, she is still a child afraid of the dark. I have given her eternity, and she uses it to mourn the world she left behind. Tell me, Kokushibo... how do I kill the human inside her without breaking the weapon I have spent a thousand years forging?" Kokushibo didn't answer. He knew there was no answer. He simply sat in the shadow of Muzan’s tirade, listening to the Demon King complain about the one thing he couldn't control: the enduring, stubborn light of your soul.