The Evening and The Sea(2017)

Yoru to Umi

"I never really wanted good friends. I always thought I'd rather have things I'd be okay with leaving behind."

Tsukiko is the new girl in school. One day, she catches a glimpse of her classmate, Utsumi, swimming in the school's pool. She becomes fixated. Tsukiko knew they were classmates, but beyond that, the two girls had no reason to cross paths. However, one rainy day turns all of that around. An emotional story about the everyday lives of the enigmatic new girl and the girl with no filter who happens to love swimming!

(Source: MangaPlaza)