Yes. Kurobuchi Maou DX (Kuro, Buchi, literally "black-spotted demon king deluxe") is a cat that lives at 4/7; he's been described as a 'black cat' in the fanbook but generally has been depicted as a white cat with black spots in most visual mediums. Luna is Hokusai's white cat. Both of them are sort of representatives for the implied multiple cats that live at 4/7 and that hang around Hokusai respectively, but they've always been different cats.