In a marriage swap, the best physical compatibility is found with the husband of a close friend or relative. (ADN-778)

Kazuka and Miyu, who have been close friends since their school days, are still husband and wife. However, Kazuka is troubled by her pregnancy and gradually accumulates complaints about their sex life. Under these circumstances, Miyu brings them an "AI compatibility diagnosis," and the four of them jokingly try "couple swapping." Originally, they just wanted to observe each other through the camera, but Kazuka being raped by Miyu's husband becomes the catalyst, and their hidden sexual fetishes are exposed, leading to a crazy and chaotic encounter...