What do you do when a game starts playing by its own rules? Shugo and Reina only recently started playing The World, the most advanced online game ever created, but they are already well on their way to becoming heroes. They've got a great party of friends, cool new items, and now they've been joined by Zefie, a Vagrant Al who acts outside the rules of the game. As intelligent as Zefie may be, the CC Corporation isn't about to let an unstable element run free in The World-not after what happened four years ago. So with the notorious debugging team, The Cobalt Knights, on the prowl, Shugo and company had better watch out!