Uwaki Biyori -Datte Kareshi to Suru yori Kimochi Iin da Mon-

Kuji Kaede who attends Nasumizu Gakuen is an examinee aiming for a national university. "The first sex I've ever had with my boyfriend wasn't so great." She despaired saying, "This isn't the sex I was looking for." She wants to experience the intense pleasure that makes her breathing difficult, and asks her sister Azusa, to introduce her to a man who is good at sex. Thus, Kaede, a serious school girl, begins her promiscuous affairs. [Translated from DLsite]