Hikari, a former secretary to a company president, remarried a man who runs a company. Even though she was a stepmother, she was concerned about her son who was a recluse at home even though he was an adult, and as a mother, she gently looked after him. One day, the stepmother went into her son's room to encourage him, and discovered her own panties that had disappeared from the laundry. Seeing her son apologise profusely in a panic, the stepmother was troubled and gently embraced him to forgive him. Then, her excited son pushed her down and tried to penetrate her...!