40-year-old Sayuri, whose husband is frequently away on business trips, often finds herself alone with her stepson. One day, while attempting to insert a tampon in the bathroom, she is caught by her son's friend who had come over to visit. Flustered, she boldly declares, "You saw my pussy, didn't you? Now show me yours!" What begins as a fleeting encounter gradually grows more intense. How will her stepson react when he senses what's going on? An unexpected turn of events awaits.