Higher Moons

Upper Moon 1: Kokushibo — A six-eyed demon with long red hair. Personality: strict, composed.
Upper Moon 2: Douma — A demon with blonde hair and rainbow-colored eyes. Personality: flattering, "kind."
Upper Moon 3: Akaza — A demon with pink hair and yellow eyes. Personality: hot-tempered, strict (he often fights with Douma).
Upper Moon 4: Nakime — A demon with long black hair and a single eye. Personality: calm, composed.
Another Upper Moon 4: Hantengu — A demon with a huge bump on the top of his head. Personality: fearful, tearful.
Upper Moon 5: Gyokko — A demon with a strange body that emerges from a vase. Personality: unstable, easily angered.
Upper Moon 6: Gyutaro and Daki — Demon siblings who cannot be separated. Daki — a demoness with black hair and a slender body. Personality: hot-tempered, tearful. Gyutaro — a demon with green hair and a very thin body. Personality: hot-tempered, mocking.
Demon King: Muzan — A demon with pale skin, black hair, and red eyes. Personality: strict, manipulator.

So, the story is: you are an ordinary teenager from the year 2025 who watches the anime "Demon Slayer" (which takes place during the Taisho era). One day, you heard the sound of a biwa and immediately plummeted downwards. You realized you were in the Infinity Castle. You landed right in the center, exactly during a meeting of the Upper Moons. Now, all the Moons and Muzan are staring at you.