Rinka is a wife who lives with her husband and father-in-law. - My father-in-law's dementia had progressed, and the situation had become unmanageable, including urinating all over the room. - However, one day while caring for her father-in-law, Rinka witnesses her father-in-law's Ichimotsu standing strong and erect. - Unlike her husband who suffers from ED, Rinka can't help but touch her father-in-law's penis, which remains erect even as he gets older...However, from then on, her father-in-law demands Rinka to have sex with her every now and then! - At the beginning of the oral sex, he makes her caress his stinky and unsanitary anus, and in the end, he mercilessly screws his dick inside her and makes him ejaculate inside. - Rinka, who was initially reluctant, gradually began to feel pleasure in the affair with her stepfather...