.hack//G.U.+

Welcome to The World, the most advanced online game ever created. In The World you can be anyone you want to be, act out your adventure fantasies and through teamwork and determination, you can even become a hero. 14-year-old twins Shugo and Rena just won a contest that lets them play as the legendary avatars 'Kite' and 'Black Rose.' Armed with the power of the Twilight Bracelet, the two must discover what is causing rogue monsters to infect The World and carry on the legend of the .hackers.

(Source: TOKYOPOP)

The story takes place in the year 2020, just three years after the events of .hack//G.U. It not only takes place in the new version of "The World" known as "The World R:X", which has become popular, but in the real world as well. The lead character is a middle school student named Tokio Kuryuu. He lives a normal life as a gamer until a mysterious girl named Ayaka Amagi transfers to his school and takes him in the game world.

Raid, a newbie Edge Punisher in The World R:2 decides to sell all of his gear and items in order to buy a rare sword. Unfortunately the sword draws the attention of a group of PKers who decide to kill him and steal the sword for themselves. Dead, naked, and penniless it seems that it's all over for Raid, when he is suddenly saved by a group of players from the Seventh Division of the guild Moon Tree. 
From .hack//wiki

.hack//Alcor takes place in the online game 'The World'. Nanase is a shy and naive girl belonging to the newbie helping guild 'Canard'. All she wants is to be with Silabus, the guild master whom she has deep admiration for. However, when the guild members are targeted by player killers (or PKs) from the guild Kestrel, will Nanase be able to brave the situation?

"The World" is a massively multiplayer online game played by more than twelve million people across the globe. Within this virtual world Haseo, a PK (Player Killer), continues an endless fight. Everything he does is for the sake of the girl Shino, who back in the real world, is hospitalized by an unexplained coma. However, on finally meeting with his sole lead, a PK called “Tri-Edge,” Haseo is dropped back to Level 1 by a mysterious power! Can Haseo save Shino now that he has lost all of his abilities? Tatsuya Hamasaki, writer of the scenario for the .hack//G.U. games, now turns his hand to its novelization!
(Source: TOKYOPOP)