The official Twitter account for Kadokawa 's Dengeki Bunko imprint noted that Volume 59 of the Dengeki Bunko magazine (cover pictured at right) published the prologue chapter for the new "Unital Ring" arc of Reki Kawahara 's Sword Art Online light novel series on Saturday. Kawahara himself noted on Twitter that the new arc's title uses a mathematical term in the same vein as the earlier Ordinal Scale title. However, he emphasized that this does not mean that he is linking the two.

Kawahara added that the Virtual Reality Massively Multi-player Online projects that have appeared in the story thus far have evolved through Sword Art Online , ALfheim Online, and Gun Gale Online. However, the setting of the new arc has everyone starting from scratch, without Wiki websites or strategy guides.

The original story began with a boy named Kazuto "Kirito" Kirigaya who enters a virtual-reality, massively multi-player online (MMO) world called " Sword Art Online ." There is no escape from this world unless the player clears the game, but "game over" means the death of the player.