Elfina: Yoru e to Urareta Oukoku de... The Animation

Despite the fact 'Elfina' is a bit harsh, it is one of the adult movies I have enjoyed most. Actually, the plot is quite standard: an imagined kingdom has been invaded by some barbarians and the princess (who is used to luxury) is turned into a sexual slave. It would be just ok leaving out one 'but'. In fact, 'Elfina' has a very strong dramatic point (though it does not reveal itself at the very beginning). However, by and by you start to learn that even the servant maid has her reasons to act this or that way, and nothing happens all of a sudden. ... The reasons of all characters are bound tightly and influence each other. By the end of the hentai everything becomes as clear as if single pieces were put together making a complete picture.
Another strong point, IMHO, is the unclear ending which leaves enough space for imagination.
However, you may be distracted by some scenes of violence...