Fifty years since the invasion, the Phantom Beasts continue their devastating onslaught, indiscriminately seeking to decimate the human race into extinction. With the military's body-count rising, Japan has been forced to enlist teenagers into battle. Mai Shibamura and Atsushi Hayami, two young soldiers of Unit 5121, have finally seen some action and are ready to take on even more Phantom Beasts. While trying to secure food supplies, they notice that the alien invaders are attacking cats, which fuels Shibamura's anger. Later, in the Arakawa war zone, orders and inexperience lead to tragedy and humiliation for Unit 5121, and both Hayami and Shibamura feel the sting of loss. This setback weakens the platoon...but not for long! The existence of the human race is at stake, and these kids were drafted to save it.