Rin and her husband hadn't had sex for almost half a year. Even when Rin invited him, her husband kept refusing, saying he was busy with work or tired. Rin, who was frustrated, had no choice but to comfort herself alone in the kitchen. One afternoon, Rin was cleaning the air conditioner, but lost her balance and fell while doing so. Her son, who came home from university, takes care of Rin. The son remembers Rin's lewd state that he peeped on last night and attacks her. That became the trigger, and the relationship between Rin and her son began. The son is excited by the sexual acts they do nearby so that his father doesn't find out, and Rin also indulges in sexual acts as she is desired…