Hiroshi Umino, a youth yearning for autonomy, abandons Earth to forge his own path, defying oppressive constraints. Constructing a makeshift spacecraft, he crash-lands on Deimos, crossing paths with the enigmatic Emeraldas. Her mentorship becomes pivotal as he navigates adversity: dismissal from a job after clashing with his employer’s daughter, targeted persecution over his unauthorized vessel, and a harrowing escape aided by a self-sacrificing benefactor.

The OVA reimagines his journey, depicting Hiroshi as a stowaway on a freighter besieged by Afressian forces. Stranded on Daibaran—a lawless desert world evoking a frontier ethos—he labors in a rowdy saloon, amassing resources for his ambitions. Confronted by adversaries like Commander Eldomain, he withstands brutal trials, his defiance unshaken. Emeraldas, witnessing his tenacity, bestows the Cosmo Dragoon, a weapon imbued with legacy from her late companion Tochiro, marking her faith in his destiny.

His origins unravel as Zero Banno, scion of an explorer executed for rallying enslaved laborers. This tainted heritage propels his quest for reinvention. Symbolism permeates his identity: “Hiroshi” (wide/open) and “Umino” (sea field) mirror his longing for boundless freedom, while “Banno” (barbarian) echoes familial ostracization.

Initially solitary, Hiroshi gradually embraces interdependence. A fleeting act—rescuing a cat from strays—hints at buried empathy, contrasting his aloof exterior. Through alliances forged amid skirmishes with cyborgs and Afressians, he learns strength thrives in unity as much as individualism.

The manga’s open-ended finale teases unresolved tension, with Emeraldas alluding to a shrouded secret destined to entangle their fates. The OVA diverges, charting his proactive role in combat, where courage and ingenuity earn Emeraldas’ regard. Departing Daibaran with comrades, he shifts from lone wanderer to collective visionary, channeling ambition into collaborative enterprise.