Momoko decides to leave her husband and reunites with her lover. During their first secret encounter, she submits to her lover Terada's passionate advances, only to be shocked when he coldly tells her their affair was nothing but a game. Returning home the next day, heartbroken and lost, she discovers her son's best friend, Hideto, lying on the sofa wearing her panties. Overwhelmed by loneliness and emotional turmoil, she gives in to temptation and sleeps with him. This single moment pulls Momoko into a twisted love triangle that will change her life forever.