Familiar is a demon supposedly attending and obeying a witch, often said to assume the form of an animal. [source]

The Kang family have been tending a witch family for generations as a familiar in a cat form. But even a thousand years won't stop Kang Daniel to put a stop to everything. He himself, the first hybrid of a normal human being and a demon in his family feels that he doesn't need to continue what his ancestors had been doing for thousand of years.

Kang Daniel, the first generation of his family to disobey the rules, the first cat to refuse seeing even just the shadow of his master. Luckily for him, the family's master wanted to put stop to everything too. They didn't want their children to live like them and practice their family traditions since they're not practicing witchcraft anymore.

"Me? Tending a human being? Maybe in my next life."  - Kang Daniel

"If I ever meet him, I truly hope we could be friends."  - Ji Mihae

For him, as a half human he shouldn't be disrespected like that. He want to be treated as a full human being too although he knows what he exactly was. He did used his cat form in certain places, but he still liked his human form more.

So there he was, living his perfect human life for the last 28 years without having to tend anyone, everyone knew him as the nice Daniel, since he is sweet and kind to everyone. Not just to humans, but to cats too. But an event changed his whole life. Just one event. The event where he met Ji Mihae.

"You really hate me don't you?" - Ji Mihae

"So what if I really do? I never wanted this marriage in the first place!" - Kang Daniel