Aoba is a young girl who loves to build models of robots. She lived alone with her grandmother until her grandmother passes away. Shortly after she is kidnapped and brought to a secret base where she discovers a huge robot. The piloted robots fight against Ancient-Jinki in The Grand Savanna, but the true meaning behind the fights is hidden. Aoba works hard at the base so one day she can pilot one of the robots and discover these secrets.

In an alternate history, following World War II, civil unrest and terrorism run rampant in a devastated Japan under foreign occupation. During a botched interception of underground munitions being transferred by a terrorist organization, Constable Kazuki Fuse, a soldier in an elite counter-terrorism unit, witnesses the true terror of human nature. He fails to prevent a teenage girl from carrying out a desperate suicide bombing that subsequently causes immense destruction to Tokyo. With mental scars and his competence under question, Fuse is sent back to the military academy for re-evaluation. Unbeknownst to him, he will soon be caught up in a web of government conspiracies that have the power to determine the future of all of Japan. As Fuse treads the fine line between human and beast, he ultimately discovers to which side he truly belongs.