Read manga: Asagao To Kase-San.

manga
Summary:

Yamada is the plant appointee; tending the school's garden of flowers on her own. She isn't the slightest bit athletic, she's actually quite clumsy - but that doesn't stop her from having feelings for the star track member in the class next-door, Kase-san. Slightly shy, Yamada is reluctant about her feelings for the enthusiastic Kase-san. Still, slowly but surely, the pair are helping each other to grow in confidence for both themselves and their budding relationship, each blush and brush of the hand at a time.