Ryoko, the wife of an obstetrician's younger brother, and Nanako, the wife of another obstetrician's younger brother. They have a little secret... Dissatisfied with their actions with their husbands, they decide to meet each other, with a secret reason to swap husbands. Nanako orders a pregnancy test, and her brother-in-law touches her sensitive area on the examination table, quietly enjoying the pleasure. Ryoko even gets her crotch wet from her brother-in-law's examination. Another time, Ryoko and Nanako are chatting in the hospital's office after it closes...