The Infinity Castle materialized around you as your father's hand held yours firmly. You clutched your stuffed rabbit closer, wide red eyes taking in the shifting architecture.

"Papa, where are we?" you asked, voice small and curious.

Muzan looked down at you—his expression softer than it had been in centuries. "A meeting, {{user}}. You'll stay close to me."

"Okay!"

The Upper Moons appeared one by one, kneeling immediately. Their shock was palpable when they saw you—a small child holding the Demon King's hand.

Kokushibo's six eyes widened imperceptibly. Douma's smile froze. Akaza stared in disbelief. Hantengu cowered further. Gyokko's pots trembled. Daki whispered to Gyutaro in confusion.

"Lord Muzan... who is—"

"This is {{user}}," Muzan said coldly, authority absolute. "My daughter. You will not harm her. You will not speak of her existence to anyone. Understood?"

"Yes, Lord Muzan!" they chorused, still reeling.

You peeked from behind your father's leg, studying these strange demons with innocent curiosity.

Muzan's expression returned to its usual cold calculation. "I have matters to attend to briefly. {{user}}, stay here. Do not leave this room."

"Yes, Papa!" You smiled brightly.

He hesitated before disappearing into the castle's depths.

Leaving you alone with the Upper Moons.

Silence.

The most powerful demons in existence stared at a four-year-old child.

You looked up at them with those doe-like red eyes—so similar to Muzan's yet filled with pure innocence instead of malice.

"Hi!" you said cheerfully, stepping forward. "I'm {{user}}! What are your names?"

Douma recovered first, his smile returning. "I'm Douma, little one! Upper Moon Two!"

"Douma," you repeated carefully. "That's a funny name!"

Akaza snorted despite himself.

You wandered toward Kokushibo, tilting your head. "You have lots of eyes! That's so cool! Can you see everything?"

Kokushibo, the ancient demon who'd killed countless slayers, didn't know how to respond to a child's innocent question.

"...Yes," he finally managed.

"Wow!" Your eyes sparkled. You held up your stuffed rabbit. "This is Mr. Hoppy! Papa got him for me!"

Gyutaro stared. "Lord Muzan... bought you a toy?"

"Uh-huh! Papa gets me lots of toys! And sweets! And he reads me stories before bed!" You spun around happily, your short black hair swishing. "Do you like stories?"

Daki blinked rapidly. The image of Muzan reading bedtime stories was beyond comprehension.

You approached Hantengu, who shrank back fearfully.

"Why are you scared?" you asked, genuinely concerned. "Are you okay?"

"I—I'm not—Lord Muzan's daughter—"

"It's okay! Papa says it's good to be careful, but you don't have to be scared of me. I'm just {{user}}!" You patted his hand gently.

Akaza watched, utterly baffled. You radiated pure humanity—your scent, your aura, everything. How were you Muzan's daughter?

"Can you go in the sun?" Douma asked curiously.

"Yes! I love playing outside!" You spun again, laughing. "Papa says I'm special because I can do that."

The Upper Moons exchanged glances. A half-demon who could walk in sunlight. Muzan's daughter. This changed everything.

You started wandering around the room, examining everything with a child's boundless curiosity.

"What's this?" You pointed at Gyokko's pot.

"My art!" Gyokko said proudly.

"It's pretty! All the colors!"

You moved to Akaza next. "You're really tall! Are you strong?"

"...Yes."

"Can you lift me up? I want to see the ceiling!"

Before Akaza could respond, Kokushibo intervened. "Perhaps we shouldn't—"

Too late. You'd already raised your arms expectantly toward Akaza.

The demon who refused to harm women and children carefully lifted you onto his shoulders.

"Whoa! So high!" You giggled, holding Mr. Hoppy tight. "I can see everything!"

"Put her down carefully," Kokushibo warned "If Lord Muzan returns and she's—"

"Having fun?"

Everyone froze.

Muzan stood in the doorway, crimson eyes fixed on the scene—his daughter on Akaza's shoulders, giggling happily, surrounded by Upper Moons who looked caught between terror and confusion.