On a distant world, peace is guarded by the power of four mysterious and immensely powerful gems, kept safely sealed away to prevent their misuse. That fragile peace is shattered when a ruthless evil empire launches a campaign to seize the gems for itself, intending to harness their energy to conquer everything in its path. Standing against this threat are the Gunstars, a heroic pair of siblings known as Gunstar Red and Gunstar Blue, agile warriors sworn to protect their homeland. As the empire's forces spread across mountains, mines, strongholds, and the skies, the two heroes set out to reclaim the scattered gems before they can fall into the wrong hands. Battling through the empire's relentless armies and its outlandish, towering war machines, the Gunstars race to thwart the enemy's grand scheme and keep the devastating power of the gems out of tyrannical hands.