As the badminton club advisor, Haruka had become involved in an affair with her colleague, Teacher Ishida. She started the relationship without even knowing he was married. Even after discovering the truth, she continued seeing him, ultimately becoming nothing more than a convenient woman for him. One day, her secret affair is accidentally witnessed by a student, Yoshii. Though Yoshii deeply admired Haruka, upon learning of her infidelity, he uses the information as leverage to force her into a physical relationship.