加速世界
In addition to the original storyline of "Sword Art Online" and "Sword Art Online: Progressive", Kawahara has also written and published "Sword Art Online" side stories. These side stories have been posted on his website, in a collection of side stories in "Accel World", have been sold at Comitia, Dengeki Bunko's Fair and have come along with the limited edition Blu-Ray/DVD "Sword Art Online" compilation volumes. Before "Sword Art Online" was published, Kawahara had posted "Sword Art Online" novels on his website and there are still a few side stories on "Sword Art Online", although the original novels have been removed. In addition, Kawahara has published a side story of "Sword Art Online" in one of his other works, "Accel World". In the tenth volume of "Accel World", there is a chapter where it depicts a cross over between "Sword Art Online" and "Accel World". Several of the side stories that he has released are in a collection called the "Sword Art Online Material Edition", sold at the Comitia "dōjinshi"-selling event, which range from novels to manga. However, all of the art in the "Material Editions" is drawn by Kawahara himself.