The mother-in-law, whose weakness was discovered by her daughter's husband, ends up having a physical relationship with him. As he hugs and kisses her, roughly kneads her breasts and stimulates her nipples, she loses all strength in her body. Though she knows she shouldn't take it any further, she willingly caresses his large penis with her mouth and allows him to insert it deep into her vagina. The forbidden erotic story of mother-in-law and son-in-law, episode 4.