In the spring of their high school days, Yuiji Hasegawa suspects that his kind but quiet classmate, Yamato Yoshinaga, has feelings for his straight best friend, Kyousuke Hongou. Ending up in the same study group, he stumbles upon Yamato holding a sleeping Kyousuke's hand, with embarrassment apparent on his face after being exposed.

Despite having qualms about Yamato's homosexuality, Yuiji keeps what he saw a secret, thus marking the beginning of their friendship. The two boys' experiences with love differ vastly, but their bond seems to grow as they try to understand each other. However, the question remains: could their relationship evolve into something more?

Koimonogatari has been published digitally in English as Koimonogatari: Love Stories by Tokyopop since May 21, 2020, and in print since June 30, 2020. The series has also been published in Polish by Dango since March 17, 2018; in Spanish by Norma Editorial since March 6, 2020; and in German by Tokyopop since June 2, 2020.