Lyoko is a virtual reality. It's full of many different monsters, and only one human being. The one true inhabitant of Lyoko, is the warrior Aelita. Despite the fact that she's the only human to live in Lyoko, she's not really alone. She has the unwanted company of the many legions of monsters. Monsters that have been created by an evil computer virus called X.A.N.A.
The monsters are the Bloks, Krabes, Megatanks, Frelions and Kankralots. They live freely within the four regions that make up Lyoko.
All of the regions that you find in Lyoko are very much like places that you'd find here on Earth. There's the Forest region, Mountain region, Desert region and the Polar region.
In each region there are ten towers, these towers can be activated by X.A.N.A. at anytime. When a tower is activated, our world could be destroyed. But it's up to my friends and me to make sure that X.A.N.A. never gets his way, and that the towers get deactivated.
My friends are Yumi Ishiyama, Ulrich Stern, and Odd Della Robbia. It's their job to travel to Lyoko and help Aelita get to the towers that have been activated, so that she can deactivate them.
Before it's too late.
I, myself however, never travel to Lyoko. It's my job to transfer my friends safely to where they need to go. And whenever X.A.N.A. awakens, we travel to an old broken down factory that has a Super Computer that is linked to Lyoko inside.
It's only from the factory's Super Computer that I can transfer my friends. And once the activated tower is no longer a threat to our world, everything goes back to the way that it was.
So all that is left to say is...
Return to the past now!