The Republic of San Magnolia has been at war with the Giadian Empire for nine years.  Though it initially suffered devastating losses to the Empire's autonomous mechanized Legions,  The Republic has since developed its own autonomous units—Juggernauts—which are directed remotely  by a Handler. While on the surface the public believes the war is being fought between machines,  in reality, the Juggernauts are being piloted by humans and all of them are the Eighty-Six, the  designation given to the sub-humans of the Eighty-Sixth Sector who are persecuted and stripped of  their rights by the racist-led Alba government.  Major Vladilena "Lena" Milizé is an Alba noble and military officer in the Republic's Military  who is assigned as a Handler of the Spearhead Squadron of the Eastern Front, an elite unit composed  entirely of Eighty-Sixer veterans who have earned names led by their squad leader,  Shinei "Undertaker" Nouzen. As Lena gets to know Shinei and the rest of the Spearhead Squadron,  she becomes sympathetic to his people's plight and tries to help them. At same time, Lena and  Shinei learn a dark secret: the Republic and the war with the Empire is not what it seems.