Takashi Katori is a big fan of online games, and so is his American friend Sarah. However, one of their RPGs goes too far, as their virtual world and the Lezarion robot that Takashi created for the game somehow mix with reality. Takashi is caught, but later the Earth Governement discovers that an evil scientist from the Moon is hacking into virtual worlds and security, so they force Takashi to pilot the Lezarion and protect the Earth...
The story is centered on young middle school student Takashi Katori and his classmate/best friend/love interest, Olivia Lawrence. Takashi, who began as a mere online game fan, developed a small virtual world with his friend David from New York, in which they played their robot combat game. They would play by sending data to each other using satellite technology. One day while they were playing, a scientific experiment using the same satellite was being conducted involving teleporting an American plane from New York to Japan. In a freak accident caused by an explosion during a rebellion by people of the moon who attacked Earth, the plane that was converted into digital information was sent to the virtual world while Takashi's robot information was rematerialized into a real robot.