In the year 2022, the Virtual reality Massive Multiplayer Online Role-Playing Game (VRMMORPG) Sword Art Online (SAO) is released. With the Nerve Gear, a VR Helmet that stimulates the user's five senses via their brain, players can experience and control their in-game characters with their minds. But an unexpected event occurs on November 6, 2022 when Akihiko Kayaba, the creator of SAO, prevents the players from logging out. Akihiko issues them a challenge; if they wish to be free and log out of the game, they must reach the 100th floor of the game's tower and defeat the final boss. However, if their avatars die in the game, so will their bodies in the real world. As the game's 10,000 players try to accept their new deadly predicament, Kirito, a skilled player who tested the beta version of the game, is determined to reach the 100th floor and attain freedom. As he befriends other players along the way, including Asuna, who becomes his partner and love interest, Kirito faces many obstacles and eventually discovers the true purpose of SAO.
After escaping SAO, Kirito, for a series of circumstances, takes part in other VRMMO games.