its one of my favourite series in the world, and its sooooo dear to my heart. ;v; last year i read akatsuki no yona and it really moved me, and though it differs to saiunkoku, it also reminds me a little of it. both the heroines are such strong, wonderful girls, and they both have the most amazing people supporting them.
i'm really sad about how the anime ended and also about how the manga ends too... *read spoilers* but it is a truly magical series and i recommend it highly to everyone. ^_^
taken from wikipedia:
Saiunkoku is a world of eight provinces or houses, each named after a different color.
Set in the fictional empire of Saiunkoku