Upon the discovery of an isolated island, its long-forgotten inhabitants are reintegrated into society. Unbeknownst to many, the island was once a sanctuary for supernatural beings, notably the infamous Onigashima from the legendary Momotaro tale. As some vengeful demons emerge to seek retribution against Momotaro's descendants, a middle school girl named Momomoto Akira finds herself reluctantly befriending a transfer student, only to become a prime target for these wrathful creatures.