In the near future the virtual community OZ, a mirror-image of reality, has been created so that anyone can easily access the internet from anywhere on the planet. People do their shopping, make payments and enjoy entertainment, just as they do in the real world, using avatars as their alter egos. Kenji spends his summer holidays idly working as a part-timer maintaining the OZ system. But then his dream-girl, lovely Natsuki, invites him to accompany her to Nagano, her hometown. There, Kenji is bewildered when Natsuki asks him to pretend to be her fiancé, but she only does so because she wants to make her grandmother happy. At the same night, Kenji receives an e-mail with a hard question in mathematics from an unidentified person. Kenji, a math whiz, tries to solve it, and when he finally finds the answer, the world is totally changed. Next morning, in a TV news, there is a story about a lawless avatar in OZ. Surprisingly, it’s Kenji. Innocent Kenji is maligned as an OZ outlaw and before he knows what is happening, he is thrown into a battle which influences the fate of the world. “The family will sort out any problems caused by our kinfolk!” At a command from Natsuki’s grandmother, Kenji, Natsuki, and her relatives tries to save the world!!