The Commoner King: The Eternals

Miraculo's father dies and he is made the new Prince of Arginine. Little does the kingdom know that their prince is actually a princess raised as a boy to protect her from being taken away and forced to become the next king. Because she is royalty she can decide if she wants to marry a male or a female which works out in her favor. She goes on many adventures as she hides her gender and men fall for her.

A different type of reverse harem.