Updated November 16, 2018: Added SAO Volume 21 cover art and exact title name.
UPDATE: Please read the latest article for the full Sword Art Online: Unital Ring story summary now that the light novel has been released. The remainder of this article remains as is since the last update.
The long-awaited Sword Art Online: Unital Ring light novel is finally going to be released by Japanese author Reki Kawahara. Based on information Reddit users provided from Kadokawa’s Dengeki Bunko imprint, the Sword Art Online Volume 21 release date in Japan is being set for December 7, 2018.
The Sword Art Online: Unital Ring story arc is the direct sequel to the story of Sword Art Online: Alicization, which is the focus of the anime Sword Art Online Season 3. SAO: Alicization was covered by volumes 9 through 18, while volumes 19 and 20 were a side story called Moon Cradle that took place before the ending of Project Alicization. Unital Ring will likely be the focus of the anime Sword Art Online Season 4.
Not too much is known about the story of Sword Art Online: Unital Ring. What makes SAO: Unital Ring different is that the previous light novels were based on the web novels written by Kawahara, whereas Unital Ring will be a new work entirely.
On Twitter, Kawahara explained that Unital Ring’s title is a reference to a mathematical term similar to Ordinal Scale. However, that does not mean the two story arcs are linked in any manner.
In the past, Kawahara had promised “one more big arc” that will go “back to the real world.” Thus far, the Virtual Reality Massively Multi-player Online projects Sword Art Online, Alfheim Online, and Gun Gale Online (and Underworld, sort of) have been the focal points for plot development, but the new story arc will have Kirito, Asuna, and all the other SAO characters starting from scratch in some manner.
Warning: The following contains minor spoilers for Sword Art Online: Unital Ring.
Back in December 2017, Kawahara published the prologue for Sword Art Online: Unital Ring in Volume 59 of the Dengeki Bunko magazine.
An English translation was created by fans and the story opens with Kirigaya Kazuto (real-life name of Kirito) musing about how his life could have been different. (Comically, he seriously thinks his character name would have been Naruto if his parents hadn’t died in a car crash.)
The prologue discusses the overall events of Sword Art Online: Alicization and also shows what has become of Alice and Kirito’s virtual daughter Yui. Kirito is meeting with both Asuna and Alice when suddenly the virtual world is shaken by an earthquake, which should be impossible in the VRMMO.
They are shocked to see that the sky has turned red with a system-wide announcement, an event which mirrors the day when Kirito first became trapped in Sword Art Online.
The exact title for SAO Volume 21 will be Sword Art Online: Unital Ring 1, which implies that Volume 22 will be Unital Ring 2. English readers will also have quite the wait for the Sword Art Online: Unital Ring story since the official English translation will only be up to Volume 15 as of December 11, 2018. Stay tuned!