The land has fallen into ruin, and children represent the last hope for humanity. One of them, Hiro, fails to live up to that purpose and decides to walk away from it all.... until he meets a girl with horns.

The fierce battle to take the Grand Crevasse begins, and Hiro is forced to watch from the sidelines. Zero Two may have left, but Squad 13 is still concerned about the way she fights.

The gang heads off to space to fight in what they believe to be the final battle. Meanwhile, Kokoro and Mitsuru stay behind to fight a battle of their own.