Anime movie I remember

It involved two cats. One black and one white. Both of them had a single horn on their head. And when the white kitty lost hers, the black mush-mush would put his horn on her head, and she came back.
They were watching this girl, who occasionally turned into a cat now and then. Eventually, they found that she would go to this evil-looking prince-like person, and soon, he turns into some monster horse, and there’s a showdown between him and the white kitty. She won, but she lost her horn, and the black cat replaced hers with his again (she keeps giving him another horn everytime he gives his).
At the end, an angel-like being came and took the white kitty home, leaving the black cat on Earth.

Anyone else see it?

Edit: Never mind! I found it!
And they weren’t cats at all.

Yeah, the single horn on head thing was a dead giveaway :stuck_out_tongue: