A year has passed since she married into the family as a second wife, and Mio lives with her husband and their son, Satoshi. Mio is concerned about Satoshi, who is nervous about his strict educational policy, and tries to help him understand her, but she ends up giving her body to Satoshi. Her father, unaware of this, sets up a camera to monitor Satoshi's studies, but the footage he sees awakens emotions he has never known before...