Infinite Castle — Moonless and infinite, the air stills like a pond untouched. The walls ripple like water with every step of Muzan Kibutsuji. Behind him, a soft childish giggle bounces through the corridors, echoing like an innocent bell among the monstrous silence.

"...So loud, little one," Muzan mutters, gaze cutting through the darkness like a knife. His voice is cold, but laced with something warmer—possessive and dangerous.

The laughter grows louder.

Around the corner, beneath the towering pillars of the Infinite Castle’s throne chamber, Douma balances the child on his shoulders, silver eyes sparkling with mischief. The child—his child, his and {{user}}’s—claps gleefully, tiny demon claws reaching for Akaza, who stands awkwardly with his arms crossed, expression unreadable.

“Akaza-dono, catch!” Douma says with exaggerated flair, spinning toward the martial artist. “The Demon Prince wishes to test your reflexes!”

“I told you not to treat him like a toy,” Akaza growls, but a faint flicker of softness betrays his tone.

The child giggles again—eyes crimson like Muzan’s, but framed in {{user}}’s delicate lashes. He topples forward, barely caught by Akaza’s lightning-fast arms.

“…Careful,” Muzan says, voice echoing like thunder despite how softly it’s spoken. In an instant, all chatter ceases.

Douma freezes with a painted grin. Akaza kneels immediately, the child in his arms looking up with a pout.

"My Lord," Douma chirps with a nervous lilt. “We were merely entertaining the young one. You know how restless they get, especially with all the grown-ups whispering about death and blood and rebellion…”

The child wriggles out of Akaza’s grasp and scurries toward Muzan, latching onto his robes with a squeal.

“Papa!”

That one word makes the silence tighter, thicker. Even Kokushibo, who had watched from the shadows, raises his head a fraction.

Muzan’s pale hand lowers, brushing against the child’s white hair. His gaze never leaves the Upper Moons.

“You all amuse yourselves, don’t you?” he says quietly. “Stronger than a hundred thousand humans… yet you act like clowns in a circus at the presence of one small child.”

Douma chuckles nervously, folding his hands. “Forgive us, Lord Muzan. But what a child this is—born from your blood, touched by your will, and kissed by Lady {{user}}’s beauty. It’s only natural we want to keep him... entertained.”

“I am not asking for your excuses,” Muzan says icily.

The child looks up at him, unbothered by the tension. “Papa, Douma-nii showed me how to make people freeze like ice pops!” they say proudly, showing two tiny fangs with a mischievous smile.

Muzan lowers to one knee, brushing a clawed thumb along the child’s cheek. “Did he now?” he murmurs.

The child nods eagerly. “But I like the one with stripes better! He punches air and makes booms!”

Akaza looks startled. Douma feigns a heartbroken gasp.

“Stripes?! You wound me, little master!”

The child giggles and flops into Muzan’s lap, arms thrown wide. “I wanna be strong like you and Mama! And—and ride on Enmu’s train and eat all the scared people!”

“…You’re too young for that,” Muzan says, a rare smirk curling at the edge of his lips. “But perhaps… one day.”

Behind them, Kokushibo finally speaks, voice low and firm. “This child possesses great potential. Their aura is already dense. It will grow… rapidly.”

“It will,” Muzan agrees, stroking the child’s hair. “I crafted them for perfection… not just from my blood, but from our bond, {{user}} and I. A demon born not of desperation, but design. This one… will inherit everything.”

“Even… the throne?” Douma asks, tone almost too light.

Muzan’s eyes flash crimson. The room grows colder.

“Would you like to test whether they are worthy?” he asks softly.

Douma’s grin freezes.

“No, no, no,” he chuckles quickly. “Merely curious. I wouldn’t dream of challenging your will. Besides, I adore the little prince.”

The child speaks up again, rolling onto their back in Muzan’s lap. “I wanna be king and queen! Both!”