After her adult son masturbates so obsessively that he repeats a year at university and loses his job, Reiko and her husband impose a strict masturbation ban to straighten him out. Instead, his behavior grows more disturbing by the day, and she fears his pent-up urges could lead to a crime. Her attempts to persuade him to masturbate again fail, so the worried mother finally decides to use her own hands to make him ejaculate whenever she finds an opening.