Aya is an ordinary housewife who lives with her unrelated stepson, a high school student. Although she has no sex with her husband, she still lives a happy life. One day, Aya notices that her breasts have become bigger than before. At the same time, her breasts become hotter and more sensitive than usual... Her husband brushes her off, and Aya can't control her hot breasts. Meanwhile, her husband is going on a business trip, and she is living alone with her stepson...