Kenji is a high-school math whiz who spends most of his time inside the popular virtual online community known as OZ. The real world comes calling when a fellow student and the girl of his dreams, Natsuki, convinces Kenji to accompany her to a summer retreat with her family. To his surprise, Kenji is introduced as her fiancé. Things get even crazier, however, when a mysterious AI uses the virtual world of OZ to create havoc in the real world. Stuck in the remote town of Ueda, Kenji must use his computer-hacking skills and work together with Natsuki's family to save the world from impending doom.