Six months have passed since the fierce battle against Administrator. Kirito has lost his right arm, and is now just a broken-down shell of his former self. Alice has brought him to the outskirts of her childhood home where they live.
A force from the Dark Territory launches an attack on Rulid Village. Alice rushes over on her dragon, Amayori. There she finds the villagers unable to flee because the Taboo Index prevents them from defying the Chief Man-at-Arms' orders.
The mysterious organization that carried out the attack on the Ocean Turtle…
It turns out to be a secret unit under orders from the U.S. National Security Agency.
And its leader, Gabriel, has battled Kirito and Sinon before…
Shasta had intended to use Administrator's death as an opportunity to propose a truce with the Human Empire, but his plans are thwarted by Emperor Vecta's return to the Land of Darkness.
The Dark Forces are now closing in on The Eastern Gate, which separates the Human Empire from the Dark Territory. Resolving to fight for humankind, Alice joins the Human Empire Forces, bringing Kirito with her.
The Final Load Test has begun, and the Eastern Gate has collapsed. Incited by Gabriel, now Emperor Vecta, the massive army of the Land of Darkness pushes on towards the Human Empire.
Integrity Knight Renly Synthesis Twenty-seven has been tasked with protecting the Supply Corps. In battle for the first time ever, he flees his post terrified allowing the Dark Forces goblins to invade the Supply Corps tent where Kirito is.
The powerful spell unleashed by Alice, the Integrity Knight, inflicts severe casualties on the Dark Forces, pulling them back from the brink of disaster.
Now that he's seen Alice, Gabriel orders his entire army to charge in order to capture her. The Dark Forces' elite Pugilists Guild arrives ahead of the main army in pursuit of Alice and the raid unit.
Asuna has logged into the Underworld using the super-account of Stacia, the Goddess of Creation. She unleashes a rainbow-hued aurora-like Sacred Art that causes landscape alteration.
Using the "landscape alteration" command, Asuna has created a bottomless gorge. The Dark Knights and the Pugilists attempt to cross over to the other side where the Human Empire Army awaits them.
Thanks to Gabriel's scheme, U.S. gamers from the real world have been granted Dark Knight accounts allowing them to slaughter the Artificial Fluctlights.
Sinon has logged in with the super-account of Solus, the Sun Goddess and rescues Asuna and the others at the last minute. Meanwhile, Leafa logs in with the super-account of Terraria, the Earth Goddess, and descends to the Underworld.
Despite its modest size, the Human Empire Army and Asuna valiantly battle the wave of American players surging towards them. But they're hopelessly outnumbered, and the Human Empire soldiers start to fall one after another.
Bercouli pursues Vecta, who's abducted Alice. After a long, vicious battle, Bercouli unleashes his secret sword skill, Uragiri, and finally defeats Vecta, despite having sustained severe injuries himself.
The traitor inside Rath turns out to be a researcher named Yanai. When Higa attempts to restore Kirito, Yanai tries to thwart the operation by holding him at gunpoint. Meanwhile, in the Underworld, Sinon confronts Gabriel.
Asuna and the others succumb to Vassago and the Chinese/Korean players. Discovering the catatonic Kirito, Vassago kicks his wheelchair over. Enraged, Klein lunges at Vassago, only to be pinned down by enemy players.
Sinon manages to damage Gabriel, but her strength has been sapped. Leafa collapses after wiping out the American players. And Asuna, her situation hopeless, gazes at Kirito. But the Black Swordsman continues to wander through his dreams.
Escaping his nightmares, Kirito regains consciousness at last. With the Night-Sky Blade in his right hand and the broken Blue Rose Sword in his left, he faces off against Vassago, armed with the Mate-Chopper, now enormous in size.
Alice and Asuna head to the World's End Altar as Kirito confronts Gabriel. Unless he can defeat Gabriel and return to the real world before the maximum-acceleration phase begins, Kirito will have to spend 200 years in the Underworld.