Log Horizon (ログ・ホライズン Rogu Horaizun) is a Japanese novel series by Mamare Touno. It was initially posted on the user-generated content site Shōsetsuka ni Narō in 2010 and subsequently published by Enterbrain since March 2011.
The novel has received four manga adaptations, with one based on the main story itself and the other three revolving around other characters in the series.
On October 5, 2013 an anime adaptation will air on NHK Educational TV.
"The series follows the Enchanter Shiroe and the other players of the long-lived MMORPG Elder Tales after they found themselves whisked away to a fantasy world identical to the game."