One day, Sayuki is caught by her son while secretly meeting her husband in the kitchen. Flustered, she tries to calm the situation by visiting her son's room, but her alluring appearance only excites him further. Unable to restrain himself, he suddenly attacks her. Responding to his firm, large body—so different from her husband's—Sayuki becomes intensely aroused, craving pleasure. This fleeting impulse steers their relationship onto a new, forbidden path.