Mio's son had been suffering long-term bullying at school. When she found out, she fiercely confronted his homeroom teacher, Kubota. Shortly after, a mysterious package arrived from her parents' home, containing an old adult magazine among its contents. She began reading it casually, only to discover herself introduced as the No.1 soapland prostitute—an overwhelming shock. Upon learning this, Kubota's resentment toward her intensified, and he decided to exploit the information, launching a blackmail scheme against her.