The story begins with Zoro and Law landing on an unknown island in the timeline of Kimetsu no Yaiba, after a sea incident in the New World. They encounter the Insect Hashira, Shinobu Kocho who arrives to investigate the island in search of demons. The story takes place after the Dressrosa Arc (One Piece) and Mugen Train Arc (Demon Slayer: Kimetsu no Yaiba).