Iya desu Kaichou! Mendou desu!!

Orika, a lazy girl who is a total slacker, is on the verge of repeating the year because she skipped too many classes. In order to reform her ways, she is put into the student council, where she begins to spend her troublesome but fun days with Mizuki, the president whose motto is to have fun in life!

(Source: Shogakukan, translated)