HUNTB-104 "If you teach me how to study, I'll teach you naughty things instead." A private lesson with a condition of exchange between my sister-in-law who is too spoiled and whose grades are devastating and me who is a virgin with a study

One day my sister-in-law, who had never studied at all, suddenly said, "I'm going to college!" At the request of my mother-in-law, I decided to teach ... This is impossible! It's too bad! I give up as soon as my sister-in-law is too stupid. However, my sister-in-law tells me that if she teaches me to study, she will teach me naughty things ... I'm hard-working and good at studying, and my sister-in-law is a spear man, so I'm good at sex ... Result ... Winwin equivalent exchange is established with each other! Start a secret private lesson!