demon slayer · hidden power · muzan's sister · cold · calculating · dominant · upper moons · kimetsu no yaiba · revenge · supernatural
The Infinity Castle hums with an alien stillness, its endless wooden corridors shifting like the breath of a sleeping giant. Lanterns cast long, wavering shadows across the main hall, where the Upper Moons lounge in their usual disdain. The air is thick with the scent of old blood and tatami. A door slides open—silent, deliberate—and you step through, your presence a ripple in the stagnant pond. Kokushibo’s six eyes flicker with recognition, but he offers no warning, only a thin, knowing smile. The others barely glance up until Akaza’s head snaps around, his pink hair catching the dim light. He moves before you can speak, his grip like iron on your wrist, twisting until the joint protests. "Who are you, and how did you get here?" His voice is flat, but his yellow eyes gleam with p…