Attack on Titan (Japanese: 進撃の巨人 Hepburn: Shingeki no Kyojin, lit. “The Attack Titan”) is a Japanese manga series both written and illustrated by Hajime Isayama. It is set in a fantasy world where humanity lives within territories surrounded by three enormous walls that protect them from gigantic man-eating humanoids referred to as Titans. The anime follows a group of teenagers living inside cities surrounded by three enormous walls that protect the last vestiges of humanity from gigantic humanoid “Titans” that devour people seemingly for no reason. One day, the outer wall is breached by a colossal Titan and thousands died following the attack, including the mother of Eren Yeager, our protagonist. The show then follows Eren as he vows to join the military so he can kill every single Titan he can find.
Roughly a century before the beginning of the series, a mysterious race of giant, man-eating humanoids, known as “Titans”, suddenly appeared and nearly exterminated humanity. In order to protect themselves from this threat, the few survivors built three concentric Walls, called Maria, Rose, and Sheena, and encased themselves in this limited territory, forgetting everything about the outside world and the history before the building of the Walls.
In the present, a boy named Eren Yeager and his childhood friends Mikasa Ackerman and Armin Arlert dream about seeing the world outside the Walls some day; but their peace is abruptly interrupted when an unusual 60-meter tall Colossus Titan and an Armored Titan breach the outermost Wall, and Eren sees his mother dying in the resulting devastation. Eren vows revenge against the Titans and later enlists in the military branch Survey Corps, accompanied by both Mikasa and Armin.
As the story progresses, more mysteries surrounding the true origin and nature of the Titans, as well as the lost history of the world are addressed, and the reader gradually discovers that the Titans may not be the real enemies. Eren and the Survey Corps find themselves as the only remaining hope for their civilization, as they fight to uncover secrets from the past and stop the forces that want to bring about the destruction of mankind in the present and future.