Koutarou, an ethnology student, visits a remote village to investigate rumors of men disappearing, only to fall prey to a seductive ayakashi named Ouka who drains his life force. Seeking a cure for the mysterious mark left on his body, he turns to a young shrine maiden named Renge, but he soon discovers that her promised "exorcism" is merely another trap designed to further consume him.
Koutarou discovers that the village is a human farm run by a powerful sex demon who intends to drain his life force. However, by utilizing a mysterious Energy Crest to boost his stamina and a secret drug to weaken his opponent, Koutarou turns the tables in an intense battle of endurance. After completely overpowering the demon, he earns her submission and unexpected devotion.