Titans, whose origin is unknown, nearly wiped out civilization a century ago. They are enormous, have little intelligence, and appear to just like eating people. A small portion of mankind managed to survive by settling in a city with enormous walls that tower over even the biggest Titans.
The rest of humanity has not seen a Titan in more over 100 years. But on that terrible day, a "Supertitan" materializes before the city and scales the wall. Eren and Mikasa, his foster sister, are made to witness as their mother is consumed alive when the Titans invade the city. Eren makes a blood oath that he will slay every Titan in existence in order to exact retribution on humanity as a whole.
