.hack//XXXX (pronounced X Fourth) is a manga serialized in the monthly magazine.hack//G.U.: The World released in September 2006. The manga is based on the original concept of Hiroshi Matsuyama and written/illustrated by Megane Kikuya. .hack//XXXX has various events that differ from the original versions of the first four .hack games, so it is consider non-canonical in keeping with the overall storyline of .hack.
The manga retells the story of the .hack videogame series simulating MMORPG called The World. The manga follows the character Kite, as he ventures through The World to find a cure for his friend Orca, who has fallen into a coma after being Data Drained by Skeith. It deviates greatly from the original story, with things like Aura defeating Tarvos on her own and Cubia having a human avatar.