Centuries ago, humanity was driven to the brink of extinction by giant humanoid creatures called Titans, prompting the survivors to build three massive concentric walls—Maria, Rose, and Sina—to protect themselves. For 100 years, the people lived in peace behind these walls, forgetting the outside world.

The story follows Eren Yeager, his adopted sister Mikasa Ackerman, and their friend Armin Arlert, whose quiet lives are shattered when a colossal Titan, far larger than any seen before, breaches the outermost wall, Wall Maria. After witnessing the horrific death of his mother, Eren vows to eliminate every single Titan and joins the Survey Corps, an elite military unit that ventures outside the walls. The series follows their brutal struggle for survival and the gradual uncovering of dark secrets about the Titans, the walls, and the true history of humanity.