Jun goes to his friend Shota's house with some friends to hang out. There, he happens to witness Shota's mother, Ria, masturbating while talking on the phone with her lover. Jun, who has always had feelings for Ria, is surprised, but is unable to suppress his youthful sexual urges at the sight of Ria's lewd behavior, and threatens to expose Ria's affair. Not wanting her son to find out, Ria makes a deal with Jun, but misreads the magnitude of Jun's desire. Ria's seemingly endless days of madness begin...