Takuya, a son, peeks at his mother Yumi's voluptuous body from the shadows. His feelings of respect for his mother have become distorted, and he can no longer suppress his desire to make her his own as a woman. "This is a present for mom," Takuya says one day, as he attacks Yumi and puts a chastity belt around her crotch. "From now on, I'll be in charge of mom's sexual desire." Yumi is unable to talk to her beloved husband about her growing desire, and before long, it reaches its limit...