Azusa's son, Koichi, is a sexual monster who thinks of nothing but ejaculation whenever he has free time. When her son loses his senses, he even sees his mother as a sexual object, which worries her, but she suddenly remembers her friend, the slut Mary Tachibana, and asks for her advice about her son. Now begins the sexual monster battle between Koichi, who has an inexhaustible sexual appetite, and Mary, who offers to satisfy his sexual needs.