I made my sister a reverse bunny slave for three days...!

For better or worse, my caring sister is enthusiastic about my private tutoring because she is worried that I can't study. They say things like, "I'll do anything if I get a perfect score," so I tried my best to study... and I've been able to become my own reverse bunny slave! At first, I kept complaining, but when I straddled my dick and ordered her to have sex, she swayed her hips so hard! She continues to become obedient and serves her with her big, exposed breasts! During the last three days when her parents were away, she was having sex with Usa-nee, who has reversed her position and exposure!