Kuyashii Kurai, Suki.

You're making my heart beat all alone stupid. The unfriendly girl, Reina is a first year in high school. Because of her childhood friend, Kojima Shin, she became the boy's basketball manager. He was like a small brat when they were in elementary school, but now he's gentle and so cool. But there's a Senpai who he looks up to. But I can't seem to stop falling in love with him...!?

(Source: Chibi Manga)