Knights of Sidonia

Earth has been destroyed by an alien race known as the Gauna, forcing humanity to cling to survival aboard the spaceship Sidonia. A century has passed since the last Gauna encounter, but military service remains compulsory. Nagate Tanikaze, raised in secrecy by his grandfather deep within Sidonia's forgotten lower levels, finds himself thrust into an unfamiliar world when he’s forced to the surface. His enlistment couldn’t have been more timely-the Gauna have returned without warning.