Attack on Titan Vol 1

Attack on Titan by Hajime Isayama. An Action manga rated Older Teen, published in English by Kodansha.

Humanity survives behind enormous walls that protect it from the Titans, giant humanlike creatures that devour people for no apparent reason. When a colossal Titan breaches the wall and his town is overrun, young Eren Yeager vows to wipe every last one of them off the face of the earth. The global hit that inspired the acclaimed anime.