Her husband quit his job and now spends every day drinking. When Iori Ryouko returns home from her part-time work, she passes the time cleaning the house. One day, her husband sees her buttocks, becomes aroused, and forcibly pins her down. At that moment, her son is secretly watching from a corner of the room. Unable to climax from the forced sex, Ryouko begins masturbating—something else her son witnesses. One day, while she is masturbating in the kitchen, her son suddenly appears, saying, "I've seen everything—when you're having sex and when you're jerking off. I can't hold back anymore," and pushes her down. From that day on, a forbidden relationship begins between Ryouko and her son, kept secret from her husband.