Oooh, you just spoiled it. :\ But that's cool, that they're related like that. Seems to be a common theme in anime I've seen... Japan has a hidden family relations fetish, or something. =P
It has a manga too, doesn't it? I wish I could find it, but it doesn't seem to be out in english. It's so much easier for me to finish a manga rather than an anime. XD