One month since the start of the fun-turned-deadly game, 2,000 players have already died, and the first floor has yet to be cleared. Kirito attends a meeting organized by fellow beta-tester Diabel, who announces to the attendants that his party, a group of characters adventuring together in a role-playing game, has found Illfang the Kobold Lord, the boss of the first floor. Parties are formed, and Kirito teams up with a young girl named Asuna. The next day, Diabel's raid group arrives at the boss' room and battles Illfang and his minions. When Illfang's health becomes low, Diabel goes for the finishing attack. Kirito attempts to warn him, but Illfang attacks down first and mortally wounds Diabel. As he dies, Diabel begs Kirito to defeat the boss and save the players. Though they destroy the boss, Kirito is accused of being a 'beater'andmdash;a combination of a 'beta-tester' and 'cheater'andmdash;for Diabel's passing.
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...