A former secretary to a company president who remarried a man who runs a company. Worried about her son who has become an adult but stays at home, she tenderly looks after him as a mother, even though she is his stepmother. One day, the stepmother goes into her son's room to encourage him and discovers her own panties that have disappeared from the laundry. Seeing her son frantically apologise, the stepmother is troubled and gently embraces him to forgive him. However, her excited son pushes her down and tries to penetrate her...!