I like this set too ^^
We had the chance to have the anime few years ago in France. The story is completely...well...
It's like all the persons are "trapped" in a story made by a fool (see card 5). Some of them are animals (the cat is the danse professor ^^;
, some don't. The girl is in fact a duck (see holo 5), she become a human to help the "prince" (card 6) to retrieve the parts of his lost heart (and memory). To do that, she become "princess tutu" (like the ugly duck which become a swan).
There is also a knight and a "princess Krahe" (daughter of the raven, it's the "bad guy" in the story).
It's a story which, beyond simple aspect, is really good. You a classical music (and opera) for each episod, some times are really funny, as the girl in his human form don't know how to danse (the action is in a school for classical danse). And if in the story you can find how it will end, it's not a classical end.
Hope you understand what I explained ^^