Otonari Ecchi - Motemen Cherry no Kiki Kaihi (Risk Hedge)

Sayaka is a college student who grew up next door to her childhood friend Ryuji. Although extremely handsome and popular, Ryuji admits to Sayaka that he's never been with anyone before (a fact Sayaka didn't even want to know), and that he needs someone to practice with. One thing leads to another, and before Sayaka knows it, she finds herself lying on her back, experiencing pleasure like she's never felt before.