Boku Wa Ou-sama is a show based on a book series by Teruo Teramura and Shizuko Wakayama. The first book came out in 1959 and 49 more volumes followed, making it one of the most popular children's book in Japan.
The books and the anime follow the misadventures of Ou-sama, a silly, gluttonous, lazy but overall very lovely and cute king as he seeks elephant eggs (they make the biggest omelets, his favorite dish!) hide toys in the forest just to prank his three wise counselors, or ride the bike around the castle.