Mari (Aoi), who is unable to suppress her body's throbbing, finds herself soothed by masturbation, and falls into an addiction where she cannot calm down unless she masturbates in the morning and evening... One day, Mari wakes up and is about to go to the bathroom when her son (Satoshi) comes out clutching his crotch. Suspicious, Mari pulls down his pants to take a look, and finds that her son's crotch is so tense that he cannot even use it... After helping her son release the pent up anger from not being able to ejaculate, Mari can't forget about his erect penis, so she goes to his room the next morning...