[Reducing Mosaic]MKON-140 I was alone with my friend's sister and felt awkward, but she turned out to be an insane bitch! She called me a 'loser' and made me reverse cowgirl cum inside.

Satoru ends up alone with his sister Karin at a friend's house.At Karin's suggestion, they play a punishment game in which the loser listens to whatever he has to say, and Satoru loses.Karin urges him to use his own chair.Satoru does as he is told, turns into a chair, notices his erection, and Karin admires it and curses him.The next day, Karin presses her again and this time they end up having sex.The sperm is squeezed out and falls into the slave.