Over 100 years before the beginning of the story, giant humanoid creatures called Titans (巨人 Kyojin) suddenly appeared and nearly wiped out humanity, devouring them without remorse or reason. What remains of humanity now resides within three enormous concentric walls: the outermost is Wall Maria (ウォール・マリア Wōru Maria); the middle wall is Wall Rose (ウォール・ローゼ Wōru Rōze, pronounced like rosé) and the innermost is Wall Sina (ウォール・シーナ Wōru Shīna, alt. "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, a giant 60-meter (200 ft)-tall Titan mysteriously appears after a strike of lightning and breaches the outer wall of the Shiganshina district, a town at Wall Maria, allowing the smaller Titans to invade the district...