"86" is set in a war-torn world where the Republic of San Magnolia is engaged in a prolonged conflict with the neighboring Empire of Giad. The Republic claims to fight using autonomous drones, but in reality, the war is waged by human pilots known as the "86," who are marginalized and dehumanized due to their ethnic background. The 86 are forced into combat as expendable soldiers, piloting unmanned mechs called Juggernauts, while the Alba, the dominant ethnic group in the Republic, live in safety behind fortified walls, oblivious to the truth.

The narrative centers on two main characters: Vladilena "Lena" Milizé, a young Alba officer in the Republic's military, and Shinei "Shin" Nouzen, the leader of a squadron of 86 known as Spearhead. Lena is assigned as the Handler for Spearhead Squadron, responsible for issuing orders remotely. Despite her initial naivety about the realities of the war, she gradually becomes aware of the systemic oppression and dehumanization faced by the 86. Shin, on the other hand, is a seasoned and stoic soldier who has witnessed countless comrades fall in battle. He carries the burden of being a "Reaper," tasked with euthanizing mortally wounded comrades to spare them further suffering.

As the story progresses, Lena and Shin develop a complex relationship built on mutual respect and understanding, despite the societal barriers between them. The Spearhead Squadron faces increasingly dire battles against the Empire's advanced Legion forces, which are autonomous drones with no expiration date, unlike the Republic's Juggernauts. The 86 are pushed to their limits, both physically and emotionally, as they fight for survival and a semblance of dignity in a war that has stripped them of their humanity.

The narrative explores themes of systemic oppression, the dehumanization of war, and the resilience of the human spirit. It delves into the psychological toll of combat, the moral complexities of leadership, and the bonds forged in the face of adversity. The story is divided into arcs that highlight the progression of the war, the evolution of the characters, and the broader political and social dynamics at play. The Republic's facade of equality and justice is gradually dismantled, revealing the deep-seated corruption and prejudice that sustain the conflict.

"86" combines intense mecha battles with poignant character-driven drama, creating a narrative that is both action-packed and emotionally resonant. The series balances its exploration of heavy themes with moments of camaraderie and hope, offering a nuanced portrayal of war and its impact on individuals and societies.