In Zero's first mission, the human researcher, Ciel, recruits the legendary warrior to fight against the anti-reploid organization "Neo Arcadia". Together, Zero and Ciel create a resistance group and put a stop to the senseless aggressions from the NAO. Once again humans and robot reploids are able to live in harmony. But for how long? In this next mission, Zero falls prey to a trap set by Neo Arcadia’s newly, self-appointed and ruthless commander. His plan is to trick Zero and use him to wreak chaos between reploids and humans once again. But, can he succeed?