Attack on Titan. 2 Before the Fall

Humanity has been devastated by the bizarre, giant humanoids known as the Titans. Seemingly unintelligent, they have roamed the world killing off humankind for years. This prequel series to the main Attack on Titan series is set before humanity had the weapons to effectively combat the Titans, when the Survey Corps was nothing but a group of ambitious soldiers who dared to dream of combating the Titan menace.