Nyatto!

Yaneda Shigeru is a guy living alone with his cat Konbu until it turns mostly into a human (she keeps her cat tail and ears) for unknown reasons. Though to Shigeru, this isn't a problem; he has a cat-girl fetish. The problem is, his cat, Konbu, is stuck-up and wants everything to be elegant to fit her high-class tastes, even her name to be something more high-class. So, they each want to mold each other to their tastes; Shigeru an elegant butler, and Konbu an obedient, cute cat-girl. Will one of them win, or will they come to some sort of mutual understanding? Summary taken from: Bod Rangzen