Masao has no money, hobbies, or girlfriend and drifts aimlessly through life until he finds an injured succubus named Mei and treats her at home. The clumsy low-ranking demon exhausted her magic by forcing her way into the human world and can no longer return. Masao agrees to help restore her power, only to learn that the sole method is repeated vaginal ejaculation. He keeps having sex and creampieing her until his semen is completely drained.