The story takes place in the Republic of San Magnolia, a nation under siege by the neighboring Giadian Empire. The empire has been carrying out its invasion using an unmanned autonomous battle drone army called the Legion. In retaliation, San Magnolia eventually creates their own drone army known as the Juggernaut. Although these drones are believed to be unmanned, in truth they are piloted by the Eighty-Six, a group of people who have been stripped of their humanity and are cast into battle as dispensable soldiers. The Eighty-Six is composed of a squadron called Spearhead and led by their field commander, Shin. On the battlefield devoid of hope where only death awaits, Shin continues to fight for a certain purpose.

Lena, an elite Republican soldier, is assigned as the new commanding officer, also known as a “handler,” to oversee the Spearhead Squadron. Lena despises the social caste system of the Republic that looks down on the Eighty-Sixers as “subhuman pigs,” and treats them as human beings. With Shin leading the young Eighty-Sixers on the battlefield and the talented and promising elite Lena offering tactical support from the rear, they stand on the front lines constantly on the brink of life and death.

Despite living in a class based-society where a pureblood such as Lena should have never crossed paths with someone of mixed race like Shin, the two of them break down social constructs and continue to fight for a brighter future.