Also known as: 僕と彼女のゲーム戦争
Boku to Kanojo no Game Sensou, is a 2011-ongoing Light Novel written by Shiwasu Tooru and illustrated by Happoubi Jin.
Follows a boy that joins the game club, in a previously all-girls high school. Copious amounts of fanservice and cosplay ensue.
It also has a 1 volume manga spinoff, drawn by Okuma Yuugo.