A working couple, Riho and her boyfriend, move into a new house with marriage in mind. Riho is excited about the prospect of a happy life, but her buttocks start moving on their own, as if they have another personality, which is a source of worry for her. While moving into her new home, she meets Okada, a struggling student. Worried about Okada's unhealthy lifestyle, Riho decides to take care of him and bring him meals, as he is working from home. Unsatisfied with sex with her boyfriend, Riho's buttocks start throbbing while she is making lunch at Okada's house, and she becomes aroused, seeking Okada's cock, who is nearby.