It has been a year since Misako became Yosuke Amamiya's wife, but her new stepson Kazuhiko is still barely acknowledging her, let alone seeing her as a mother figure. However, there is a more pressing matter on her mind: when she is alone at home, she frequently receives menacing calls from a stranger possessing detailed knowledge of her day-to-day life. Unable to bring this issue up with Yosuke, she remains silent about these disturbing interactions. Just as Kazuhiko starts warming up to Misako, things take a darker turn when she gets a sex toy delivered to her door. Left unsatisfied by her workaholic husband, she begins to engage in a new pastime: masturbating while on the phone with the unknown speaker. One day, Misako realizes that she is not the only one with a dirty secret when she witnesses Kazuhiko pleasuring himself with her underwear! Now aware that her stepson thinks of her as a woman, where will all this sexual tension lead?