Single mother Chisato decides to remarry, believing her son is now old enough to accept a new family. Their new life together with her fiancé progresses smoothly, until one day the son accidentally witnesses his mother having sex in a private moment. Shaken by shock and surprise, he becomes overwhelmed with intense desire and jealousy upon seeing the woman he loves being pleasured by another man. When his feelings of love and attachment for his mother reach their limit, he can no longer suppress his emotions and forcefully pins her down. This shocking turn of events sends new ripples through their family bond.