Worried that her son shows no interest in the opposite sex, Ayako Inoue becomes increasingly concerned. Overwhelmed by her worry, she decides to personally teach him about sex. Starting with masturbation techniques, Ayako's instruction gradually deepens, going far beyond just deflowering her son, eventually leading to a forbidden relationship between them. Unable to satisfy her desires in a sexless marriage, Ayako finds herself drawn to her son's body, and their bond grows ever more intimate.