When Iroha got married ten years ago, she became a wife to her husband and at the same time a mother to a son who was in middle school. Her husband had a son with his previous wife and she was worried about whether he would be able to get along with her, but they got along fine. However, she had not had sex with her husband for many years and was frustrated. One day, my husband bought a balance ball. When I invited my son to exercise with me on a balance ball, he became excited. The son starts massaging Iroha's butt. Iroha resists and tries to run away, but her son pushes her down...