Sword Art Online

Synopsis

Kazuto visits Andrew, who explains that the screenshot he sent originated from "Alfheim Online" (ALO), a VRMMORPG where players take the role of fairies capable of flight. He explains that the figure resembling Asuna was spotted somewhere on the game's World Tree. Discovering that RECTO (the company for which Sugou works) created the game, Kazuto is convinced that Asuna is trapped in the game. Wasting no time, Kazuto logs-in to ALO as "Kirito." He discovers that he still has his SAO game data, including skill levels and the SAO in-game item containing Yui's data, which he activates to bring Yui into ALfheim as a Navigation Pixie. Yui deduces that the game is made using a copy of SAO's servers, explaining why Kirito's statistics, a piece of data from SAO had been carried over to Kirito's ALO avatar. (Source: Wikipedia)