After a fight over something trivial, Shinji's wife goes to bed in a sulk, so he tries to make up with her by having sex with her. He squeezes her plump ass and cums inside her. Feeling better than usual, he goes for a kiss...but it turns out it's his wife's sister! "I'm so sorry, sister-in-law!" Shinji kneels down and apologizes, but his sister-in-law can't stop her body from throbbing.