Log Horizon (ログ・ホライズン, Rogu Horaizun) is a Japanese novel series written by Mamare Touno and illustrated by Kazuhiro Hara, published by Enterbrain in Japan since 2011. Yen Press began publishing an English translation in 2015. The series follows the strategist, Shiroe, and the other players of the long-lived MMORPG Elder Tale after they find themselves whisked away into the game world following a game update.
The novel has received four manga adaptations, with one based on the main story and the other three revolving around characters in the series. An anime adaptation aired on NHK Educational TV between October 5, 2013 and March 22, 2014. A second season aired between October 4, 2014 and March 28, 2015.
By its eleventh expansion pack, the massively multiplayer online role-playing game (MMORPG) Elder Tale (エルダー・テイル Erudā Teiru) has become a global success, with a user base of millions of players. However, during the release of its twelfth expansion pack: Homesteading the Noosphere (ノウアスフィアの開墾 Nōasufia no Kaikon, sometimes mistranslated as Novasphere Pioneers), thirty thousand Japanese gamers who are logged on at the time of the update suddenly find themselves transported into the virtual game world and donning their in-game avatars. In the midst of the event, a socially awkward gamer named Shiroe, along with his friends, Naotsugu and Akatsuki, decide to team up so that they may face this world, which unfortunately has now become their reality, along with the challenges and obstacles ahead of them.
Log Horizon began as a light novel written by Mamare Touno. It initially appeared in installments on the user-generated content site Shōsetsuka ni Narō ("So You Want to be a Novelist") starting on April 13, 2010 and subsequently published in book form by Enterbrain since March 2011. Yen Press obtained the rights on its light novel imprint to release the novels in English from 2015.
The novel series has received four manga adaptations, all written by Mamare Touno. The first adaptation is illustrated by Motoya Matsu and titled, Log Horizon Gaiden: Honey Moon Logs. It began serialization on January 27, 2012, and is published by ASCII Media Works in the Dengeki Daioh magazine. The second adaptation is illustrated by Kazuhiro Hara and titled Log Horizon. It began serialization on May 18, 2012, and is published by Enterbrain in the Famitsu Comic Clear web magazine. Yen Press obtained this manga for an English release. The third adaptation is illustrated by Koyuki and titled, Log Horizon: The West Wind Brigade. It began serialization on July 9, 2012, ended Mar 9, 2018, and is published by Fujimi Shobo in the Age Premium magazine. The last adaptation is illustrated by Sōchū and titled, Log Horizon Gaiden: Nyanta-honcho Shiawase no Recipe. It began serialization on December 21, 2012, and is published by Enterbrain in the Comic B's LOG magazine.
A 25-episode anime adaptation produced by Satelight aired on NHK Educational TV from October 5, 2013 to March 22, 2014. The series was streamed as a simulcast by Crunchyroll in North America and other select parts of the world. A 25-episode second season produced by Studio Deen began airing on October 4, 2014. Both seasons have been licensed by Sentai Filmworks in North America for digital and home video release. For both seasons, the opening theme is "database" by Man with a Mission featuring Takuma while the ending theme for the first season is "Your song" and for the second season it is "Wonderful Wonder World", both performed by Yunchi.