This Is War (Attack On Titan / Shingeki no Kyojin)

"Several hundred years ago, humans were nearly exterminated by titans. Titans are typically several stories tall, seem to have no intelligence, devour human beings and, worst of all, seem to do it for the pleasure rather than as a food source. A small percentage of humanity survived by walling themselves in a city protected by extremely high walls, even taller than the biggest of titan. Now they live peacefully, until one day..."

Genovia Hayman is broken when the day an colossa titan destroyed the city walls and the city was quickly submerged with smaller titans who begins devouring on the villagers. Genovia was soon to meet her fate when a titan grabs her and puts her in its mouth, but her Papa hurries to save her and takes her place. After watching her father being eaten alive, she promise herself to kill all titans for her Papa and all of mankind.