Attack on Titan (Japanese: 進撃の巨人 Hepburn: Shingeki no Kyojin, lit. "Advancing Giants") is a Japanese manga series written and illustrated by Hajime Isayama. The series began serialization in Kodansha's Bessatsu Shōnen Magazine on September 9, 2009, and has been collected into 14 tankōbon volumes as of August 8, 2014. It is set in a world where humanity lives inside cities surrounded by enormous walls as a defense against the Titans, gigantic humanoid creatures who devour humans seemingly without reason. The story initially centers on Eren Yeager, his adopted sister Mikasa Ackerman, and their childhood friend Armin Arlert, who join the military to fight the Titans after their home town is invaded and Eren's mother is eaten. As the story progresses, the truth behind the origin of the Titans arises and the story shifts to one about political subterfuge. A spin-off light novel series began in December 2011, and has received a manga adaptation. An additional light novel series and three additional spin-off manga series are also being serialized, and a television anime adaptation produced by Wit Studio and Production I.G aired in Japan on MBS between April and September 2013. Four video game adaptations developed by Nitroplus staffers in collaboration with Production I.G were announced to be released as bonus content for the third and sixth volumes of the Blu-ray Disc release of the anime, with another game developed by Spike Chunsoft for the Nintendo 3DS. A two-part live action film adaptation is also in production and set to premiere in 2015. Attack on Titan and three spin-off manga are published in North America by Kodansha Comics USA, while the novels are published by Vertical. The anime has been licensed by Funimation for North America, by Manga Entertainment for the United Kingdom, and by Madman Entertainment for Australasia.
Attack on Titan has become a commercial success, with 40 million volumes in print as of July 2014. The release of the anime also saw a boost in the series' popularity, with it having received 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.