War has been running so long nobody remembers why it started, and that meaninglessness becomes the real enemy. Sara and her classmates pilot Strains not because they believe in Union or Deague, but because the machine is all they have. The show strips away the heroic veneer of mecha until you're watching children operate weapons systems in a conflict nobody can justify, and that's a harder story to watch than any explosion.
Humanity splits into two warring superpowers locked in a conflict so old nobody remembers how it started. The Union pilots massive mecha called Strain while their enemies field unmanned Tumoru units across the stars. Sara Werec, a sixteen-year-old military academy student, trains to become a Reasoner, one of the elite pilots who command these weapons in battle. Her older brother Ralph vanished nine years ago on a classified mission so far away that even the fastest spacecraft needs centuries to reach it. When he suddenly reappears, aged only slightly despite the impossible distance, he brings questions that threaten everything Sara thought she understood about the war, her family, and the true nature of the Strain program itself. As Sara confronts her brother's mysterious return and her role within the military machine, the line between duty and truth becomes increasingly blurred, forcing her to question who she's really fighting for and why.