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 boobs 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 I can study, I’m not good at naughty things. Even though I was nervous, I had to ask my brother to teach me all the pleasant things!