桃源暗鬼

Shiki Ichinose, a teenager living an ordinary life, is suddenly attacked by a mysterious man from the "Momotaro Agency." While fleeing with his adoptive father, Shiki learns that his pursuer is a descendant of the legendary Momotaro, and he himself carries the blood of an oni (demon). Thrust into a hidden world, he discovers a millennia-long conflict between Momotaro’s descendants and oni descendants. Shiki grapples with his newfound identity and the powers tied to his oni heritage as he faces dangerous encounters. His journey begins to unravel the truth behind the ancient feud and the motives of both factions. (Unreviewed summary by Grok 3)