The Inoue family lives an ordinary life, but the wife, Ayako, and her only son, Tetsuro, share a secret that they cannot tell anyone. A secret... that is, the fact that they have fallen into an incestuous relationship. Although they say they want to break it off, their bodies are drawn to each other and they cannot stay apart. On the contrary, they are addicted to the pleasure of having sex at close range with their husband, who should not be found out at all. And today too, their silent sexual intercourse becomes more and more intense...