Sister "Nana" is a serious honor student. When I was studying in my room, my older brother came in and gave me a massage, but his hands became more and more naughty and my breasts were fisted... Zero experience with men. On top of that, "Nana", who is weak against pushing, decides to have sex with her brother as it is! Even if you can study, you can't do anything naughty. Even though I was nervous, I had to ask my brother to teach me all the pleasant things!
