The series began in Kodansha's Bessatsu Shōnen Magazine on September 9, 2009, and has been collected into 24 tankōbon volumes as of December 2017. It is set in a world where humanity lives in cities surrounded by enormous walls; a defense against the Titans, gigantic humanoids that eat humans seemingly without reason.
The story initially centers on Eren Yeager and his childhood friends Mikasa Ackerman and Armin Arlert, who join the military to fight the Titans after their hometown is invaded and Eren's mother is eaten and Eren swears to avenge her. However, as the story progresses and the truths about the Titans are slowly revealed to the reader, the narrative shifts to encompass Historia Reiss, squad leader Levi, Eren's father Grisha, and other supporting characters.
The spin-off light novel series Before the Fall began in December 2011 and has received a manga adaptation. Two additional light novel series and four additional spin-off manga series have also been created. An anime television adaptation is being produced by Wit Studio and Production I.G, airing in Japan on MBS. The first season aired between April and September 2013, the second season aired between April and June 2017, and a third season is scheduled to be released in July 2018.
Attack on Titan has become a commercial success. As of December 2017, the manga has 71 million copies in print, making it one of the best-selling manga series. The release of the anime also saw a boost in the series' popularity, with it having received widespread critical acclaim for its atmosphere and story. Although it also gained fame in neighboring Asian countries, the series' themes have been a subject of controversy.