あえかなる世界の終わりに

The protagonist, having lost his family because of the faulty A.I. of a machine, makes his living as a professional player of a game called CQ shot.

Suddenly your friend requests you to be a bodyguard for a strange girl who is getting stalked. The protagonist doubt whether or not there actually is a stalker but since the girl seems very afraid, he takes on the job and she starts living with him.