In a flashback, on September 14, 2025; Sinon, who had accidentally fallen down a trap chute while navigating a dungeon below SBC Gurokken, discovered a boss-class monster and decided to die while trying to defeat it. To her surprise, the position she chose for her attack was out of the monster's attack range, thus, by conserving her ammo and accurately hitting the boss's weak spot, she was eventually able to defeat it and acquired a new sniper riffle, the PGM Ultima Ratio Hecate II.
After Sinon successfully attacked the first target of another squadron for her own's, she attempted to snipe the second target, but that giant man named 'Behemoth' manage to dodge the bullet, took out a heavy machineballoon, which was hidden under his cloak, and started fighting back with its overwhelming power which cornered Sinon and those in her squadron. But in the aftermath of battle Sinon emerged victorious even if her left leg was cut-off in the process.
Meanwhile, in Alfheim, Kirito planned to tell Asuna about something.
In the near future, a Virtual Reality Massive Multiplayer Online Role-Playing Game (VRMMORPG) called Sword Art Online has been released where players control their avatars with their bodies using a piece of technology called Nerve Gear. One day, players discover they cannot log out, as the game creator is holding them captive unless they reach the 100th floor of the game's tower and defeat the final boss. However, if they die in the game, they die in real life. Their struggle for survival starts now...