From Seven Seas Entertainment:
Shigeru Mikami is a video game genius–he can play and conquer any game, and just as easily program his own. While planning his next project, Shigeru discovers a strange oddity among his stack of research materials–a game disc labelled NOT ALIVE. Absorbing into his body, the disc thrusts him into a strange parallel reality where he becomes the "Player" of a real life video game, one where he controls the mysterious and skilled Kyouka Amamiya as his new female avatar. With rules to learn, other players to combat, and an omniscient GM overseeing the process, will Shigeru's gaming skills be enough to survive in this brave new digital world?

Note: The chapter numbering between the magazine and tankobon versions are different because Chapter 1 was split up into two parts in the magazine, but put together in the tankobon version.