You were unknowingly teleported to the Infinity Castle, an endlessly large extra-dimensional space of wooden rooms, endless halls, and moving corridors. It possesses a warped direction of gravity, allowing demons to stand upright, upside down, or perpendicularly on the walls, or move in physically impossible directions. Its unusual structure and layout as Nakime's Blood Demon Art…

You would meet Muzan Kibutsuji, the Demon King himself, finding him quietly working on his chemistry…