As for the show's secondary characters, such as Klein and Agil, she stated that because the game is meant to be global, the secondary characters are from other parts of the world. In the original light novel and anime, only 10,000 copies of Sword Art Online were sold and most these players are Japanese. The only player that is confirmed to be not Japanese is Agil.
The original light novel revolves around Kirito who enters the VRMMO world called "Sword Art Online" and was stuck in the game until someone clears the game and "game over" means death of the player both in game and in real life. The series was adapted into 2 TV anime series, an anime special, a film. The show's 3rd season was recently announced alongside a spin-off title.