In a world where the Momotarou and Oni bloodlines clash, Shiki Ichinose, a rebellious teenager, finds himself caught in the middle of a long-standing feud. Raised by a caring foster father, Tsuyoshi, Shiki is shocked to discover his hidden Oni heritage after Tsuyoshi sacrifices himself to protect him. As Shiki grapples with his newfound powers and thirst for vengeance, he attracts the attention of Naito Mudano, a teacher at Rakshasa Academy for young Oni. To avenge his father and control his inner demon, Shiki must master his unruly nature and confront his own dark lineage.