In a future where Mars is submerged under water, humanity survives on city-ships drifting across vast oceans. Living conditions are harsh on the red planet, with a struggling economy, limited jobs, and scarce food supplies. Gram and his companions face the challenges of this unforgiving world as work becomes increasingly scarce. To combat government corruption, some have turned to piracy, including the notorious crew of the Ship of Aurora. As Earth sends military pilots in cutting-edge mechas known as Round Bucklers to restore order, Gram unexpectedly finds himself entangled with these pirates. Despite being on the run, he discovers a newfound affinity for his unconventional companions, blurring the lines between friend and foe.