After discovering that his stepmother Nana secretly masturbates in the bath, Kou ta knows it's wrong but can't help peeping. One day, while cleaning the bathroom together with Nana, Kou ta accidentally sprays her with the shower hose. Surprised, Nana gets completely soaked, her braless breasts becoming see-through. Unable to control his arousal, Kou ta gives in to his instincts and pins Nana down.