Accel World GU is a crossover fanfiction between Accel World and the .hack//GU series. It is set primarily in the world of Accel World with elements of .hack present. It is written by Kinji Takakura, who has written fanfics regarding Hyperdimension Neptunia.
The storyline is the same as the events of .hack//GU, however in this world, Ryo Misaki is a Burst Linker by the name of Black Reaper, and continues his role as "The Terror of Death". Shino was his childhood friend, as well as the one who introduced him to Brain Burst, and has unknown ties with Ovan, or rather the Burst Linker Azure Rebirth.
Like the events of GU, Shino was killed in front of Ryo's eyes, and since then, he has been on the hunt for the one who killed her, the Burst Linker wreathed in blue flames. According to the rumor, regardless of Burst Points and Level, if this particular player kills you, you never return to the Accelerated World. Ryo has taken one several PK (Player Killers) in the last six months, and it wasn't until meeting the student council president at his school and reuniting with Ovan that Ryo got his chance to take on the Burst Linker who killed Shino, the one named Tri-Edge.
However, in the Accelerated World, everything can change in a mere second. And Black Reaper is about to learn that the hard way...
Accel World GU's incarnation of Haseo, and a Level 8 Burst Linker. In reality, his name is Ryo Misaki, a student in junior high, ironically the same school that Arita Haruyuki and Kuroyukihime attends. His guardian was his childhood friend Shino, and unlike most players, he only played Brain Burst to hang out with his guardian and his friend Azure Rebirth, who Shino called Ovan. However, six months prior to the story, Shino was killed by Tri-Edge, a mysterious Burst Linker, and since then, Black Reaper searches high and low for him, and during his search, killed 100 PK's in a single battle, thus christening him "The Terror of Death". Strangely, Ryo's Duel Avatar is one of the few with a seemingly human appearance, beairng a flesh and blood face.
The Duel Avatar of Shino, Ryo's (Black Reaper) childhood friend and Guardian. She was the one who introduced him to the world of Brain Burst and through her, he met Ovan, who was called Azure Rebirth. According to Ryo, her Avatar was one of the few that could heal other players. However, six months prior to the story, she was killed by Tri-Edge. As stated by Ovan, her Burst Points were stripped from her, Brain Burst uninstalled from her Nuero-Linker, and since then, has been placed into a coma. It was because of this that Ryo had become the Terror of Death, the Burst Linker who slaughtered 100 others in a single night.
Better known as Ovan by Ryo and Shino, he is a Burst Linker shrouded in mystery. His real identity is unknown, and due to how deep his voice sounds, many people believe him to be an older male, despite the requirements to play Brain Burst. Since the destruction of Shino's Duel Avatar, Ovan has been missing for the past six months. Ovan's Duel Avatar is arguably more human-like than Ryo's, however his entire left arm is encased in a giant cylinder with some kind of lock on it.
The Traitor of Brain Burst, The Black King, these are but two of the monikers granted unto Kuroyukihime, the player behind the Duel Avatar of Black Lotus. She is the Guardian of Silver Crow, the only player with the Aviation Ability. It is unknown how she learned about Black Reaper's true identity, however she seems to be very interested in him, and had even made him the offer to join her Legion, a means of protection from the Six Kings of Pure Color due to Ryo's activities and monstrous power. She is one of eight Level 9 Burst Linkers, and Ryo's main love interest in the story.
A myth-like Burst Linker wreathed in blue flames. He has never once been seen, however he bears a human-like appearance, much like Ovan, and his power is unreal, far above even that of the Six Kings of Pure Color themselves. According to the rumors, any Burst Linker who Tri-Edge destroys, regardless of Burst Points and Level, will never return to the Accelerated World, and as learned by Ryo, those players will enter a coma. The scene where he supposedly appears bears a crude triangle that is etched into the ground, as if marking his kill. As noted by Ryo, he exhibits absolutely no emotion at all.
A Burst Linker with the Aviation Ability, the first every character with the power to fly. In reality, he is a middle school student attending the same school as the player of Black Reaper and Black Lotus, and is actually a good friend of Ryo's in online games. He was actually a subject to bullying and had an inferiority complex, as he hated being pitied by his friends Chiyu and Taku until he met Kuroyukihime and entered the world of Brain Burst.
Accel World GU has a few areas that can be found in .hack//GU, such as Hulle Grandz Cathedral. Also, Ryo's Duel Avatar, Black Reaper, has the appearance of Haseo's third form in the game, and as stated by the author, he would gain his Xth form sometime later on in the series. The Epitah Avatars have not yet made an appearance. Black Reaper's unique skill is called 'Multi-Weapon', and as seen so far, Ryo's weapons are his dual blades, chainsaw-blade broadsword, and scythe.