Jun has been living with his wife's mother, Yuu, for a year now. Even though he is his mother-in-law, Jun is captivated by the beauty of Yu. She has an adult charm that his wife does not have, an overflowing maternal instinct, and a sexy body that seems to be inviting Jun... Even though he knows it is wrong, Jun keeps his eyes on Yu every day. One day, Jun accidentally witnesses Yu changing clothes and cannot suppress his feelings for her...