The plot of Attack on Titan centers on a civilization inside three walls, the last location where humans still live. Over one hundred years ago, humanity was driven to the brink of extinction after the emergence of humanoid giants called Titans, who attack and eat humans on sight. The last remnants of humanity retreated behind three concentric walls and enjoyed nearly a century of peace. To combat Titans, the country's military employs Vertical Maneuvering Equipment, a set of waist-mounted grappling hooks and gas-powered propulsion enabling immense mobility in three dimensions.