Kirito, along with his childhood friend, Eugeo, has been tasked with cutting down a colossal tree called the Gigas Cedar. They’re swinging their ax when their friend Alice arrives with lunch. As they eat, the three friends decide to go to a fabled cave.

Kirito wakes up to find himself inside a mysterious world evoking a fantasy game. His memory fuzzy, he tries to log out, but is unable to return to the real world. After wandering aimlessly, he finds himself underneath a colossal tree.

Asuna infiltrates Rath, the research lab in the Ocean Turtle, where she relentlessly grills Kikuoka about Kazuto's whereabouts. Kikuoka reveals that behind the development of the Soul Translator is a mind-blowing objective of epic scale.

Two years have gone by since Kirito and Eugeo left Rulid Village. In the capital city, Centoria, both boys have attained their goal of being admitted to the North Centoria Imperial Swordcraft Academy.

Kirito and Eugeo are now considered criminals for having violated the Taboo Index and are thrown into the underground prison in the Central Cathedral. Meanwhile, on the Ocean Turtle in the real world, Asuna is watching over Kazuto as he's being treated.

Kirito and Eugeo have been rescued by the young girl, Cardinal, who has secluded herself inside the Central Cathedral’s Great Library. Cardinal explains to Kirito how the Axiom Church and the Taboo Index came to be, starting with Administrator’s past.

Though riddled with wounds, Kirito manages to activate his Perfect Weapon Control art. Continuing on their way to the top floor of the Central Cathedral, Kirito and Eugeo find themselves standing before a strange-looking floating platform.

Eugeo reaches the ninetieth floor of the Central Cathedral, which turns out to be a vast bathing area. The perplexed Eugeo encounters Bercouli Synthesis One soaking in the bath. Meanwhile, Kirito and Alice are still climbing the Central Cathedral wall.

Carrying the hopes of Cardinal, Eugeo, and Alice in his heart, Kirito stands yet again and visualizes the Black Swordsman, the top player who cleared SAO. For the sake of everyone he’s encountered in this world, Kirito, faces off with Administrator.

A force from the Dark Territory is attacking Rulid Village. Though she’d lost her purpose in battle, in order to fight for her family, and for the people that Kirito and Eugeo tried to protect, Alice takes up the Osmanthus Blade once again!

Upon seeing Alice, Gabriel orders his entire army to capture her. The pugilists guild races ahead of the main force. As Alice and Bercouli try to come up with a strategy to counter them, the silent Integrity Knight Sheyta Synthesis Twelve steps forward.

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.