Miho gave birth and got married at a young age, but gradually the relationship became sexless, and when her son became a university student, she discovered her husband's affair. While she and her husband were living separately with divorce on the cards, her son returned home for the summer vacation. On a trip to a hot spring to tell his mother about the divorce, his son confesses that he had always loved his mother. Kokoro is touched by her son's kindness more than by her cold-hearted husband, and although she knows it is wrong, her sense of guilt as a mother and the joy of being a woman are torn apart. In a small inn deep in the mountains, mother and son lose themselves in love... A mother-son incest story!