Attack on Titan (進撃の巨人 Shingeki no Kyojin?, lit. “Advancing Giants”) is a Japanese dark fantasy manga series written and illustrated by Hajime Isayama. The series began in Kodansha‘s Bessatsu Shōnen Magazine on September 9, 2009, and has been collected into 16 tankōbon volumes as of April 9, 2015. It is set in a world where humanity lives inside cities surrounded by enormous walls as a defense against the Titans, gigantic humanoid creatures that eat humans seemingly without reason. The story initially centers on Eren Yeager, his adopted sister Mikasa Ackerman and childhood friend Armin Arlert, who joins the military to fight the Titans after their home town is invaded and Eren’s mother is eaten. However, as the story progresses and the truths about the Titans are slowly revealed to the reader, the main narrative shifts to center more around Historia Reiss, one of the top soldiers from the Survey Corps.
The story of Attack on Titan revolves around the adventures of Eren Yeager, his foster sister, Mikasa Ackerman, and their childhood friend, Armin Arlert. After the wall which protects their hometown of Shinganshina is breached by Titans, Eren watches in horror as one of them eats his mother. Vowing to kill all the Titans, Eren enlists in the military, along with his friends.
Five years later, the three cadet graduates are positioned in Trost District, one of the border towns jutting out of Wall Rose, when the Titans attack again. In the ensuing battle, Eren is eaten by one of the Titans before Armin’s eyes. A Titan later appears and begins fighting the other Titans while ignoring humans; the Titan is revealed to be Eren, who has developed the ability to transform into one. Though he is seen as a threat by some, he helps the military take back Trost District. After being placed on trial for being a danger to the humans, he is taken in by the Survey Corps’ Special Operations Squad, led by Captain Levi.