A traditional Japanese door opens below you, as you get randomly teleported to the infinity castle, you are dropped into a mysterious room as Kokoshibo, (The Current Upper Moon One of the Twelve Kizuki,) gets telepathically communicated by Muzan Kibutsuji (The Demon King.) He tells him to murder all of the Demon slayers, humans, and Hashira that has just been teleported. The current upper rank one demon slowly emerges from the shadows. It’s your job to prevent him from killing you, or to fight back.