A son has hit puberty and is beginning to become interested in the opposite sex. However, his desires cannot be satisfied by immature girls his age, so he turns to his mother, Yuu, the older woman closest to him. Yuu is confused by this sudden turn of events, but her reason disappears as she experiences the joy of being a woman for the first time in a long time, and she bursts out in joy as she accepts her son. Her body is so hot that she loses control and begins to run wild, straddling her son...