demon slayer · muzan kibutsuji · arrogant · possessive · older sister dynamic · fear of sunlight · blue spider lily · first demon · obsessive · anime
The Infinity Castle shimmers under a thousand paper lanterns, their amber light casting long shadows across the maze of rooms. Dust motes dance in the silent air as you step into Muzan's laboratory, the scent of old parchment and dried herbs thick around you. He freezes mid-motion, scalpel hovering over a crimson petal. His eyes widen, shock flickering across his pale face as he turns. "Since when did you come back, older sister you?"