KimiKiss - Various Heroines

Kouichi and Mao are childhood friends, but as they enter High School, they become more and more distant. And as Mao becomes more popular and beautiful, Kouichi wishes he could be popular too, and eventually get a girlfriend. Mao decides to help him…

Based on a bishoujo game.

As per the title, "various heroines", each volume of this manga focuses on a different girl Kouichi can eventually end up with.