Found this awesome anime last night called Spaceship Agga Ruter. It was done by the same people that did Tenchi-Muyo, and the art style and animation is very well done. The story is funny and at times quite serious for a hentai show, somewhat like Masqarade(little bit of naughty then some seriousness). Anyway, I was pleasently surprised when out of nowhere one of the main characters, a space pirate named Jannis turns out to be a "Modified Human" or a Human who's DNA was spliced with beasts in order to survive in very hostile environments. In the first episode, after having sex with our hero, she turns into a were-cat version of herself, and it was done really well in my opinion. There's only 4 episodes of this anime and outside of this episode, the rest of her transformations aren't really as serious(she actually turns into a cute little cat that the hero carries around everytime somebody captures them), and outside of one scene where Jannis reverts from cat, to beast to human, she doesn't get another transformation scene, but hopefully if this link works, you'll get to see the first and best one. Let me know if this link doesn't work, and tell me what you think of it. Sorry for the long post, I just love finding little transformations off of random anime.
http://www.rapidsharing.com/759e679d...8ca775150d7111