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.
In an alternative, middle-ages setup, the human population is dwindling in numbers. With the advent of Titans, giant humanoid creatures that attack and devour any human on sight, what remains of civilization is protected by three concentric walls, hundreds of kilometers long and around fifty meters tall. Eren Jeager, a young boy whose father disappears after his mother is killed during the fall of Wall Maria. Years later he enlists into the army, accompanied by his adopted sister Mikasa Ackerman and their childhood friend Armin Arlelt. He later discovers that he possesses the ability to temporarily transform himself into a Titan. Seen as a threat by some, and a ray of hope by others, Eren joins his companions in a war to protect what still remains of mankind,