PPPE-275 I made my obedient big-breasted younger sister wear an obscene costume, conquered her breasts, and fucked her unrivaled in an erotic game.

Yu, a socially misfit and NEET, stays at home and spends his days indulging in erotic games. Yuu had wanted to try out the erotic play he learned through erotic games someday, so he decided to try it out on his cheeky younger sister as an experiment. Let's play a punishment game where you play an erotic game and listen to whatever the winner says! Yu, who won by a landslide, makes his big-breasted sister wear an obscene costume...