My sister, who is kind to me for better or worse, worries about my studies and diligently tutors me. She says, "If you get a perfect score, I'll do anything," so I studied hard... and made her my exclusive reverse bunny slave! She started serving reluctantly, but when I ordered her to have sex while straddling my dick, she started cumming like crazy with her hips bouncing! Gradually becoming obedient, her face melts... she actively does fellatio and titty fucking! Training completed to my liking! During these 3 days when my parents are away, I'll cum inside my masturbation sister bunny as much as I want!