HUNTB-104 "If you teach me how to study, I'll teach you dirty things." A private lesson with exchange conditions between my slutty stepsister whose grades are terrible and me, the studious virgin.

One day, my sister-in-law, who hadn't studied at all, suddenly said, "I'm going to college!" At the request of her mother-in-law, I decided to teach her, but... This is impossible! I can't do it! I give up on my sister-in-law who is too stupid as soon as possible. However, my sister-in-law says that if she teaches me to study, I will teach her naughty things. I'm a hard worker and good at studying, and my sister-in-law is a bimbo, so she's good at sex. Result…A win-win equivalent exchange was established! Start a secret private lesson!