Yumi, the female prison guard, was renowned for turning even the most violent inmates into model prisoners. Using her large, mature, and shapely ass as a weapon, she employed a special, highly lewd method of control—fitting prisoners with chastity belts, then forcing them to stimulate her ass underneath. As a result, the inmates diligently served their sentences, disciplining themselves daily in hopes of earning Yumi's ultimate reward: the exquisite blessing of ejaculation release. Her presence commanded respect throughout the prison, and her techniques continued to exert a powerful influence over countless inmates.