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