It revolves in a world where humans live behind three huge walls to protect them from giant creatures that eat humans, and centers around the young "Erin Yeger" and his friends "Mikasa" and "Armin" after a huge giant appears breaking the wall and killing Erin's mother, so they swear to join the "Scout Corps" to fight the giants and reveal their secrets, to discover that the giants are transhumans and that there are deeper conflicts behind the walls of the alleged peace.