Soredemo Sekai wa Utsukushii

In the almighty Sun Kingdom, it never rains. In the Rain Dukedom, select women of the royal family have the ability to call the rain with song. So when the most powerful ruler in the world, the Sun King Livius Orvinus Ifrikia, decides it's time to take a wife, it only makes sense that he demand to marry one of the four princesses of the Rain Dukedom, an offer they can't refuse. (imdb)