Sexfriend

Sexfriend (セックスフレンド) is a hentai computer game and anime. Sexfriend focuses on the protagonist, Takabe Tomohiro who has his first sexual encounter in the nurse's office after school with his classmate, Hayase Mina. He eventually desires a real romantic relationship, not just friends with "benefits and cookies". Another student, Nonomiya Kaori, sees Tomohiro and Mina having sex and runs off disappointed because she loves Takabe. She eventually joins them in a threesome.