.hack//XXXX, pronounced "X-Fourth", is a manga version of Kite's adventures in the previous .hack games, serialized in the .hack//G.U. The World magazines. Individual manga volumes of the series became available in Japan in late 2006, and in North America June 2008.
In XXXX Aura appears before Kite and Orca bearing the Twilight Bracelet. With an enigmatic message that "you have the power to resolve this" she gives the bracelet to Orca and vanishes.
Skeith appears before Orca and Kite shortly after Orca receives the Twilight Bracelet from Aura. Orca attempts to fight Skeith, but Skeith renders all of his attacks useless and destroys him with his Data Drain attack. Before he can finish off Kite, Helba appears and drives the Phase off.
Balmung works as an agent of Lios. He holds Kite responsible for the disappearance of Orca, and attempts to attack him in their first meeting, only stopping when BlackRose and Mistral step in to defend Kite. Confused he continues watching Kite from a distance.
Much later, a stronger Kite encounters Skeith while in a field with BlackRose and Mistral. After a hard and mostly unsuccessful battle, Kite manages to unleash the power of the Bracelet, destroying Skeith.
While Balmung confronts Kite after the defeat of Skeith, the human avatar of Cubia tracks down and destroys Innis. Lios observes this happening, and later shows Balmung a recording. The fight makes Cubia realize that he is not strong enough to defeat all the Phases alone, leading him to team up with Kite.
Kite runs into Elk while wandering around in a field filled with Aromatic Grass. Elk thinks that Kite has come for the Aromatic Grass, to try to steal Mia from him. Before Kite can explain that it's a misunderstanding, Magus suddenly appears. Kite's first instinct is to use the Bracelet, but he decides not to since he was just warned by Lios that using it damaged The World. Kite tries to tell Elk to run away, but when Elk sees Magus destroying the field and its Aromatic Grass, he tries desperately to fight it. When he realizes all his attacks are useless Elk begins to panic. Magus prepares to Data Drain him but Balmung pulls him out of the way at the last moment. The worst effects of the Data Drain are avoided, but Elk is knocked unconscious. Balmung charges into battle, demonstrating the skill that made him known as one of The World's greatest players, but to no effect. Seeing Balmung about to share Orca's fate, Kite attacks Balmung, knocking him out of the way of Magus's attack. The next Data Drain is aimed at Kite, but Cubia drops into the way, launching his own counterattack which destroys Magus.
Fidchell is easily defeated by the party of Kite, Balmung, and Cubia.
Gorre is attacked and defeated by the combined efforts of Kite, Balmung, and Cubia. Though the Phase's two parts pose a challenge to the fighters, Kite and Cubia are able to defeat it with a double data drain attack before Gorre has a chance to reveal Cubia's identity.
After defeating Gorre, Cubia pretends to be Mia to send an e-mail to Elk, inviting him to an area. But in that area, an insane Mia is waiting, defeating Elk. At that time, Kite and Cubia arrives. Cubia says that Mia is a liar who made players become coma victims. Then, Mia transforms into Macha. In the battle, Kite find that Elk was still conscious, but he still decides to destroy Macha. However, the power of the bracelet is out of control, making Kite feel dizzy. When Cubia is about to Data Drain Macha, Elk stops him, said "No matter whether Mia is an AI or not, she's still my friend." Hearing Elk's voice, Macha starts to come to consciousness as Mia. Thanking Elk for catching Macha's attention, Cubia destroys Macha suddenly. BlackRose, Balmung, and Helba come after the battle. BlackRose blames Kite that he killed Elk's friend just for his convinience, deciding to break away from him.
Tarvos appears in Mac Anu while Kite is missing. It does quite a lot of damage to the town, and is about to kill BlackRose when Aura destroys it. Knowing that Kite's being along with Cubia, Aura warns BlackRose that Cubia is the anti-existence of the bracelet, and he will takeover Kite. To save Kite, BlackRose reaches Cubia's place after fighting with plenty of Gomoras, seeing a monster-form Cubia and unconscious Kite lying. "Don't you want to save your friend?" BlackRose screams, then destroys the bracelet, making monster-form Cubia disappeared.
Kite wakes up in Net Slum and reunites with BlackRose, Mistral, Natsume, Balmung, and Helba. When Kite wonders if he can defeat the last phase without the bracelet, Corbenik appears, Data Draining Mistral, Natsume and BlackRose. In the fierce battle with Corbenik, Kite and Balmung are heavily damaged, and Helba is crushed in Corbenik's hand. At this desperate moment, brought out by surviving Cubia, Orca appears. Then, Lios tunes up the three PCs' parameter to the maximum, making them defeat Corbenik. However, Corbenik reformed into the second form, as Morganna's avatar. Aura comes at the moment Corbenik(Morganna) beat the three PCs easily, requesting Corbenik(Morganna) to kill her. Kite tries to stop her, mentions that Aura is not just a data, and "The World" is not just a game, starting attacking Corbenik(Morganna). Inspired by Kite's words, Aura receives his attack, given birth again as the Ultimate AI. The reborn Aura gives Kite a brand new power, turning him into Azure Kite. At last, Corbenik(Morganna) is completely destroyed under Azure Kite's attack.
After the crisis, Aura claims that she will keep an eye upon "The World" as the Ultimate AI. Then everyone can play "The World" normally. Finally, Kite confirms that Cubia is still alive because he's not only the bracelet's but Kite's anti-existence.
- Due to contradictions with the original plotline of the games, XXXX is considered non-canon.
- At the very end of the second volume a picture is shown of how Orca, Balmung and Kite look in real life.
- During the ending of the story, Kite transforms into a form greatly resembling Azure Kite, right down to the swords; Empty Skies.