The Seventh Planet

In the first year of the Empire, the world was divided by a strict hierarchy into three realms: Gold, Silver, and Iron. At the edge of the galaxy lay the forgotten Seventh Planet. He was a special forces officer who survived a battle but lost his faith in combat. So he scraped by on the Seventh Planet as a schoolteacher, opening a school of his own. While salvaging a scrapped mech, he rescued an extraordinarily handsome man, who turned out to be the son of the leader of Feisha's self-governing territory.