Yamaoka Momosuke, a writer of children's riddles, becomes disillusioned with his work and sets out to compile a collection of dark and unsettling tales. As he delves into the world of myths and legends, he encounters the Ongyou, a trio of detectives who investigate these stories to uncover the truth behind them. Their mission is to bring those responsible for the atrocities to justice, forcing Momosuke to confront the darker aspects of reality. Each encounter with the Ongyou tests his moral compass and forces him to question what he is seeing, plunging him into a world of horror and the unknown.