Reiko marries into the founding family of a large company and lives a wealthy life. However, her husband is all about work and doesn't care about his family, and recently his sexual desire has dried up... Unlike her husband, she has been drawn to her kind-hearted son, Kousuke. Reiko was troubled by her hidden love for her son, but her spell was broken by a letter. It turns out that Kousuke is the child who was mistaken at birth. Kousuke is saddened by this fact. However, since he secretly saw Reiko as a woman, he couldn't resist and pressed his hot and wet lips together...