Kanojo no Kanojo to Fujun na Hatsukoi

Historia

"In exchange for my help with your studies, you must stay let me stay at your house until summer vacation." If I get a failing mark again, my chance to live by myself will be over. So I'm forced to go along with the proposal from Tsukasa, the smartest and most beautiful girl in school. But then I saw them. I saw Tsukasa kissing a girl in the park. Tsukasa, who often annoys me with her abnormal invasions of my personal space, has a “girlfriend." Her yuri friend is against this arrangement because she thinks it's “cheating” even if it's between two girls, but Tsukasa is having none of it.

Sinopsis vía AniList (en inglés).