Attack On Titan: Volume 1
Several hundred years ago, humans were nearly exterminated by giants.
Giants are typically several stories tall, seem to have no intelligence and who devour human beings. A small percentage of humanity survived barricading themselves in a city protected by walls even taller than the biggest of giants. Flash forward to the present and the city has not seen a giant in over 100 years - before teenager Eren and his foster sister Mikasa witness something horrific as the city walls are destroyed by a super-giant that appears from nowhere.