Tsukasa Tenma is the personal butler of Prince Rui of the Dark Kingdom. Tsukasa is originally from the Light Kingdom, but he carefully hides this and does not reveal why he decided to become a butler for the royal family. And the reason is that his younger sister is sick and he needs a huge amount of money to find her a doctor. He just does his job perfectly, even if sometimes he can be stubborn and overly responsible. He also sees Rui as a carefree guy who doesn't understand his situation.