As a tester for the world’s first medical-use Full-Dive device, Yuuki has been diving into virtual worlds from the hospital. Unable to leave her hospital room, she longs to go to school again. To make that wish come true, Asuna asks Kazuto for help…

A few days have passed since Yuuki suddenly disappeared from in front of Asuna, and she still hasn’t logged in to ALO. Later, Asuna meets Kazuto on the school roof, where he hands her a note and tells her Yuuki might be at the location written on it.

Asuna and the Sleeping Knights’ attempt to defeat the boss on Floor 27 has been observed by a guild specializing in boss raids. Now 20 of its members block the boss room. With Kirito stalling the rest of the guild, can Asuna and the others break through?

Asuna is asked to help the guild “Sleeping Knights,” which has decided to disband soon due to the members’ circumstances. Before they do, they want to defeat a Floor Boss with only their party.

Armed with a large sniper rifle, Hecate II, the young girl Sinon is making a name for herself as the No. 1 sniper in GGO. When her squadron ambushes another squadron, she succeeds in taking out her first target. But when she takes aim at her second target, a robed “Behemoth,” he dodges the bullet.

Hearing rumors about a brilliant player known as Zekken, Asuna decides to mount a challenge. But when Asuna logs out, she is told by her mother to take an exam to transfer into an academically oriented high school.

In an upcoming update of ALO, Floors 21-30 of New Aincrad will be unlocked. Asuna, Kirito and Yui revisit their dream of once again living together in their log cabin on Floor 22.

Kirito and the others are taking on Thrymr, the Boss lurking at the bottom level of the dungeon. But unable to make much of a dent in Thrymr's HP, they soon find themselves in grave danger. Just then, their new ally, Freyja, raises her voice…

Kirito and the others are tasked with subjugating the Frost King Thrymr, and a quest to recover Excalibur. It's Yui's guess that this isn't a quest planned by the game admins, but something automatically generated by the system. And if that's the case…

It's reported that the Holy Sword Excalibur has been discovered inside ALO. Hearing the news, Kirito and Leafa decide to take possession of Excalibur before other players get to it first.

Debriefing of the events of Sword Art Online II so far…

Kyouji attacks Shino, saying he'll kill himself after she's dead. Kazuto saves her at the last second by jumping Kyouji. During the fight, Kazuto is hit with Kyouji's poison syringe, but miraculously it doesn't work and Kirito is saved. The next day Kazuto and Shino go to meet Kikuoka, and discuss the incident. Kikuoka has a message from one of the captured Death Guns...

Death Gun's attack is modeled after Star Splash, a SAO skill that doesn't exist in GGO. Death Gun is skilled with not only a gun but a blade as well, and he gradually wears down Kirito's health. Meanwhile, Sinon's scope has been destroyed by Death Gun and she cannot attack, so she's forced to simply watch the fight. She grits her teeth and wonders if there's anything else she can do.

BoB nears its end, and the only surviving players are Kirito, Sinon, and Dark Wind, the second place winner of the last tournament. Since Death Gun may have multiple partners, and Dark Wind may be in danger as well, Kirito decides to defeat him first. He acts as a decoy while Sinon snipes the enemy. Kirito's trust in her pays off as her bullet strikes true, and he finally faces off with Death Gun.

After escaping from Death Gun, Kirito and Sinon lay low in a desert cave. There, Kirito speculates on how Death Gun murdered other players. In doing so, he hits upon a certain terrifying possibility.

Sinon is attacked from behind by Death Gun and paralyzed. He's using a Black Star Type-54, ironically the same gun that Sinon used to shoot the robber. Her memories of the incident come flooding back and Sinon loses control, and Death Gun tries to kill her to make Kirito angry. But just before he can kill her Kirito saves her at the last second. Sinon is out of the fight, and Kirito tries to flee with her but is pursued by Death Gun.

A year has passed since SAO was cleared. Summoned by Kikuoka of the Virtual Division at the Ministry of Internal Affairs and Communications, Kazuto learns of a series of bizarre murders linked to the popular VR game, Gun Gale Online (GGO), the only game in Japan played by pros.

The final round of Honnouji Academy’s Naturals Election is about to begin and the Elite Four all want to be the first to fight Ryuko. Her homeroom teacher, Aikuro Mikisugi, is concerned if she’ll be able to make it through one fight, let alone all four!

Satsuki Kiryuin reveals her plan to rebuild Honnouji Academy’s order, a free-for-all whose survivors will be able to regain their Goku Uniforms. Despite the resulting chaos, Ryuko and Mako go for a ride, only to wind up in an unexpected situation!

After defeating another group of clubs, Ryuko notices her opponents are becoming more and more absurd. Mako points out the reward for beating her is a Three-Star Goku Uniform and a higher quality of life, which prompts Ryuko to come up with a plan.