What happened in .hack//Infection was just the beginning , prepare for the true battle to begin in .hack//Mutation.
Soon after Kite and his team are defeated by a powerful monster called Cubia which appears moments after defeating Skeith which was the monster that put Orca into a coma in the real world thanks to it's data drain powers , they begin to think that this could be a sign that the true battle was about to begin very soon but soon trouble begins to come Kite's way as the System Adminstrators along with their leader Lios begins to believe that Kite's mysterious bracelet is the cause of all the problems in the game world so he believes that in order to keep the infection from spreading he trys to delete Kite's character data but is soon saved when the legardary hacker Helba appears to say that it maybe something else doing the problems then tells the pig-head to observe the young Twin Blade and his friends for awhile long so now that his butt was saved he can continue his quest to find the cure for Orca and all the other comatose victims.
Kite gets to team up with alot of cool characters as each one has his or her own personally behind their character from each other as all the characters that he has met in the first volume of the game series return to play ( except for Orca who as I said before is still in a coma ) so if you like making friends then you will be happy to know that you are able to get five brand new characters to join in your adventures which include Nuke Usagimaru the Long Arm , Rachel the Blademaster , Moonstone the Twin Blade , Marlo the Blademaster and finally Wiseman the Wavemaster.
There is alot more stuff that Kite can do in his new game which include exploring the many areas of the game world , leveling up your characters , playing a game of tag with those goblins from the last game again , raise grunties to enter into the Grunty races which becomes open once you have raised all three different types on each server except for Delta that is , collect stuff to use in your travels or give them to your friends to make them happy , face off against more Data Bug bosses including two that are from the same monster family as Skeith was , go to the area Hidden Forbidden Holy Ground to see special flashbacks of same of your favorite charactrs from the .hack//Sign tv series plus this is the biggest feature of all that id you have a saved file from .hack//Infection that has a data flag save on it then you can convert it over to .hack//Mutation as whatever character level and items you had will be transmitted over to help you be more prepared for what lies ahead of you.
The .hack series is by far one of my favorite products to have ever come out of Japan so if you interested in trying it then the choice is yours plus this is good to know also that if you have or haven't played the first volume and just started to play the second game , when you start the game it will always explain to you the events that happens over the course of the game so please enjoy.