A princess' order is absolute.
Kanojo to no Tadashii Asobikata starring Kurokawa Tomoka, Mizushima Hiro and Hamada Gaku.
Himura Yuna and Fujiki Kyouji are primary schoolmates. While sitting in the rain unwilling to go home, Yuna suggest to Takeshi that they play a game. To play the game Yuna is the princess and Takeshi is the servant. When they are at school or out in public that act normal and rarely acknowledge each other but when it's just the two of them, Takeshi must treat her as a princess. Takeshi asks how long the game will last and Yuna replies that it will last forever or until someone finds out about it.