hino-san no baka
A Japanese yuri manga written & illustrated by Kinniku Tarou.
Class president and overall good girl Koguma is concerned that her classmate Hino often skips classes by spending her time behind one of the school buildings. Koguma feels it's her duty to guide Hino down a better path, even if it means going along with Hino's unusual requests.
-from dynasty-scans.com