Attack on Titan is a Japanese manga series written and illustrated by Hajime Isayama.Over one hundred years prior to the beginning of the story, giant humanoid creatures called Titans suddenly appeared and nearly wiped out humanity, devouring them without remorse or reason. What remains of humanity now resides within a country surrounded by three enormous concentric walls: the outermost is Wall Maria; the middle wall is Wall Rose and the innermost is Wall Sina. Inside these walls, humanity has lived in peace for one hundred years; many people growing up without ever having seen a Titan. This all changes when one day, within Eren Yeager\'s hometown, the Shiganshina district which juts out of Wall Maria, a giant 60-meter (200 ft) tall Titan known as the Colossus Titan mysteriously appears and breaches the outer wall, allowing smaller but still deadly Titans to infiltrate the district. Many are killed and the wall separating Shiganshina from the lands within Wall Maria is breached when a second Titan smashes clean through. Mankind is forced to abandon the land between Wall Maria and Wall Rose, evacuating the remaining population into the inner districts. The sudden influx of population causes turmoil and famine.