Yuko lives with her daughter and her husband while her husband is on a business trip. She felt extremely lonely when she couldn't be with her husband, but it seemed she wasn't the only one who felt that way. Toru, her son-in-law, also often masturbates in the middle of the night. Yuko knows how uncomfortable it is to have sexual desires that are not satisfied. A daughter's responsibility is also her responsibility, so she must help Toru relieve all of his long-accumulated sexual desires.