Nono has been married only a short time, but her husband has already been away on a three-month work assignment. Worried about her living alone, her adult sister and brother-in-law invite her to stay with them. The peaceful arrangement soon gives way to frustration, and Nono masturbates almost every day. Then she learns that her brother-in-law Tetsuya is also suffering through a sexless marriage—and that he has an exceptionally huge cock. Unable to suppress her aching desire, she secretly seduces him. Tetsuya eventually gives in to her devilish advances, and their affair begins to consume him.