Manga by Hero Academia Mangaka "HORIKOSHI Kouhei". totally unrelated to Hero Academia.
On the once-peaceful planet of Industria, constant battles have been fought over control of the planet. Astro is a dim witted but kind boy who tirelessly works to feed his "family," a group of orphaned children. One day, after being fired from his most recent job, the prince of Industria, Bulge, appears in front of him. And even more shocking, Prince Bulge looks and sounds exactly like Astro! One thing leads to another, and Astro now has to take Bulge's place as the heir to the throne of Industria! Suddenly, he's faced with the task of bringing peace and harmony back to this war-torn planet!