The discovery of alien life has turned the once serene planet Industria into a world of racism and perpetual conflict. Young orphan Astro lives his life with one goal: to work hard and earn enough wages to care for a group of fellow orphans he has adopted as his own family. Astro's simple life is disrupted when he encounters Bulge, the Crown Prince of Industria who is his age and shares his exact face. The prince is fleeing his royal obligations in pursuit of debauchery.

The royal military captures Astro after mistaking him for the prince, ripping the young orphan away from the family he cares about. With the King of Industria misidentifying Astro as his own son, the boy is forced into the royal lifestyle. He spends his days training in the art of combat under the high-ranking young soldier Tiamat, whose only perceivable weakness is a crippling fear of women.

After foiling an assassination plot and awakening the powers of the ancient lance Orgue, Astro is sent off with Tiamat to train with his new weapon to end the petty conflict between humans and aliens across the planet's surface.