Sex-starved Yuna discovers that her adult son's adult friend Kosuke masturbates to her and secretly decides to sample him. But his tireless cock stays hard even after one or two loads. At first she enjoys being pounded by him almost every day, but his relentless stamina gradually pushes her past her limits. Kosuke keeps making her cum at full force until her overwhelmed body can no longer take it and finally screams for relief.