Attack on Titan

In a world entirely ruled by giants, the human race, which has turned into their food, has surrounded its residential zones with immense walls, which both prevent their freedom outside the walls and protect them from incursions. However, as a result of the appearance of supergiants who cross the wall, a desperate struggle begins and the young heroes, who have lost their parents, fight the giant as a training corps, with a view to regaining their freedom.

(Shingeki no Kyojin)