Kiri no Prizrak

The nations of Erde and Morye are at war. Adam, a tank commander in the Morye army, survives against the forces of Morye and their biomechanical ant warriors thanks to his close bond with his comrade Lev. Ordered to extract information from a captive soldier from Erde due to his understanding of the language, Lev discovers an imminent assault from the dominant forces of Erde; an assault that will plunge Adam deep into the fog of war, and force him to understand the nature of his enemies...

(Source: Shufu to Seikatsu Sha, translated)