Worried that her adult son has no interest in sex, Yurine offers to show him her naked body as a form of sex education. Her careless gesture unleashes the obsessive desire for his mother that he has kept hidden. While his father is away on business, the adult son loses control, restrains Yurine's limbs, and makes her climax again and again. As her reason gradually collapses, she stops begging for her husband and craves only her adult son's cock.