Due to his father's sudden transfer, nephew Dai moves in temporarily with his aunt Reiko (Riri Koda) and her husband, the Kitayama family. One night, Dai secretly spies on his aunt and uncle's intense lovemaking and can't help but start masturbating. From that night on, Reiko's seductive image constantly haunts Dai's mind. His heart gradually becomes consumed by an affair with his aunt. The day when this fantasy turns into reality finally arrives.