Originally based on a novel by Reki Kawahara, Sword Art Online is an acclaimed anime series that follows the adventures of its young protagonist, Kirito, within the next-generation Virtual Reality Massively Multiplayer Online Role-Playing Game known as Sword Art Online.
This latest entry in the series is based on an all-new “War of Underworld” story arc unique to this game and features more characters and episodes than ever before in order to portray a setting different from that of the source material and anime.

Story
If Kirito and Eugeo were here...
The threat of annihilation draws near for Underworld, a virtual world designed to give birth to the supreme AI known as A.L.I.C.E.
The “Final Stress Test” served as the beginning of the end... The gate dividing the Human Realm and the Dark Territory has been thrown open, causing the shadow of war to be cast over the two realms.
Just then, a dark knight accompanied by a young girl bursts through the gate before Kirito and his companions...
“What’s the difference between the world ending and me dying?” Who is this girl that is seemingly destined to meet a tragic fate and ultimately brings about an unavoidable “end” of all things?
With the answers to such questions shrouded in mystery, a tale of life itself is about to unfold...