Summary

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 Before entering the story of the main characters and the following in the anime, I prefer to place them in the world that goes Attack on Titan to give one more chance to give in as it gives time for anyone to start seeing the anime my fault and say that I did not warn you (not that I want you not to watch, the truth is that I wanted aLL attend, however, I know that not everyone likes this anime style, so ...).

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A hundred years ago, giant creatures suddenly appeared humanoid shapes in our world, and for some unknown reason, they eat humans as they are one. These giants, known as "Titans" are not necessarily intelligent, but because they are huge (between 3-15 meters high), are in large quantities and simply show up, they basically decimated humanity. The few people left over, survived because they settled in a reign with very high walls ("wall") formatted in three concentric circles: Wall Maria Wall Rose and Wall Sina. Thanks to these walls, humans were able to survive for a hundred full years without titans attack within the cities, and the only humans who died were those who entered the army as a patrol officer, the group who venture into the outside of the walls to try to find out something more about the mysterious titans and how they can be eliminated forever.