In 2022, the Virtual Reality Massively Multiplayer Online Role-Playing Game (VRMMORPG), Sword Art Online (SAO), is released. With nerves Gear, virtual reality helmet that stimulate the five senses users through their brains, players can feel and control in their game characters with their thoughts.
On 6 November 2022, all players logging in for the first time, and then find that they can not log out. They were then told by Kayaba Akihiko, creator SAO, that if they want to be free, they must reach the 100th floor tower game and beat the last boss. However, if they die in-game avatar, their bodies will die in the real world. The story follows Kirito, skilled players who are determined to beat the game. As the game went on for two years, Kirito eventually befriended a woman named Asuna players with whom he eventually falls in love. After the duo discover the identity of avatars Kayaba at SAO, they face and defeat him, freeing themselves and other players of the game.
After returning to the real world, Kirito and Asuna learns that a small group of players SAO still not awake yet. After a hint of Asuna in another VRMMORPG called Alfheim Online (ALO), Kirito also log in there. Suguha assisted by his brother, he learned that the players stuck in ALO is part of a plan devised by Nobuyuki Sugo illegal to conduct experiments on their mind to put them under his control, including Asuna, which he intends to be married in the real world in the ordered to take over the family firm. After stopping Kirito Nobuyuki plan, he finally reunites with Asuna in the real world.
Soon after, Kirito play another game called Gun Gale Online (GGO) to investigate the mysterious relationship between it and the deaths that occur in the real world. Aided by a woman he met players in the game called Sinon, he eventually identify and expose the actors that includes several former members of the guild killer previously encountered in the SAO.
Kirito is then recruited to assist in the development of the game state-of-the-art, Underworld (UW), which has an interface that is much more realistic and complex than previous games he had played. At UW, the flow of time takes place thousands of times faster than in the real world. However, he finally fell into a trap set by one of the killers of GGO and wake up in the game, can not log out, the self is actually left in a coma. As he began to question whether he is real or artificial intelligence Kirito modeled after her, Asuna, Suguha and Sinon also log themselves into the UW in an attempt to help him.
