Ryoko is the wife of her elder brother who is an obstetrician, and Nanako is the wife of her younger brother who is an internist. They both have a little secret... Not satisfied with their own husbands, they decide to secretly swap husbands, each with a reason to come to the doctor's office. Nanako says it's a pregnancy test, and on the examination table, her brother-in-law palpates her private parts, quietly enjoying the pleasure. Ryoko's crotch also gets wet from her brother-in-law's examination. The wife comes back for another examination... One day, Ryoko and Nanako pass by the brothers chatting in the office after closing time...