It is said that there is a fitness gym with a reputation that even the most slender man can get the body of the goal if he joins. Reiko, who is an instructor at a seemingly unremarkable gym, used a secret membership management method to stoically work on body remodeling. The method was to give a "reward" of ejaculation only to the members who put on a chastity belt with lustrous buttocks as a bait and achieved results. Members dream of ejaculation every day and continue to train at the gym.