Shige, a young man, is secretly attracted to his friend's mother, Chihiro. One day, when he returns to retrieve something he forgot, he witnesses Chihiro being blackmailed over a past mistake. Shige sympathizes with Chihiro, but when he sees a sex photo from the past, he becomes aroused and forces Chihiro down. Chihiro refuses, but Shige's shameful caresses arouse her. She gradually becomes addicted to a lewd orgy with her son's friends...