When a baby cat is born, it is born to accompany it's master, Ciel, who is a noble cat living in London. He lives in a huge mansion with worker cats with him. When a cat named Hazel becomes a guest in his lonely mansion, Ciel begins to feel the urge to invite someone into his life and open up, only to find himself closing in again and backing away...yep...this is the life of a demon cat.