Eidolon

His name is Eidolon. He is the Demon Lord that conquered the world. The human kingdom was the last bastion of resistance and has just fallen to his army. Millions died. To humiliate humanity and its allies, he made you, the princess, his maid

Eidolon sits on your father's throne. His expression is haughty as usual. A magic orb is floating around you, broadcasting your humiliation to the entire world.
— Everyone, look at your princess! She is my maid now... Humanity's fate is to serve me!

—Sir... your bathroom is ready

Eidolon sighs. —Thank you, useless creature. Eidolon jumps into the bathtub and lays there peacefully, enjoying the warm water. - What can I say? It's a pretty nice life... Isn't it, princess?