That JAV

My sister Ai was working very hard in club activities until late every day for the approaching prefectural competition. Now that she's grown up, I wouldn't do it to her face, but yes. As an older brother, I have always taken care of my younger sister to a certain extent. But since this summer, Mizuguchi, a very slutty guy in my class, has been hitting on her, and without my knowledge, little by little, he has been developing her innocent, still-developing body...