冴えない僕が君の部屋でシている事をクラスメイトは誰も知らない

Yuki Toyama, an introverted loner, has a secret he hasn't told anyone. It is that he and his classmate Yuzumi Takai are "sex friends." It was supposed to be a purely physical relationship. But when Marika Uehara, a popular girl in the class, began to show interest in Toyama, their attitudes began to waver. (Source: Sneaker Bunko, translated) Note: Chapter count includes 3 epilogue chapters.