A virtual reality gaming system known as the Nerve Gear is finally released to the public alongside the world's first virtual reality game called Sword Art Online (SAO). Kirito, one of the game's beta-testers, logs-in to Aincrad, the world of SAO and quickly befriends novice player Klein, to whom he teaches the basics of the game. After a few hours, Kirito and Klein discover that they cannot log-out. Akihiko Kayaba, the game's creator and employee of the computer corporation Argus, announces to the players that he intentionally removed the log-out option and that all players will die if their Nerve Gear is forcefully removed or their in-game health bar is depleted to zero. He informs them that he created this game as a way to become God over his own dominion. The only way to escape is to clear all 100 floors of Aincrad.

Kirito tries to overcome the dungeon alone, after 2000 players die.

Kirito rescues a guild from a monster attack and then joins them.

Kirito rescues a young beast-tamer named Silica.

Asuna offers to buy dinner for Kirito, but their meal is interrupted by a scream. They rush out of the restaurant to find a player, Kains, hanging outside a church, impaled with a spear. He dies immediately after. Fearing there is an unknown player versus player skill, they began to investigate the murder.

The "Murder in the Area" is investigated by Kirito and Asuna.