I'm really liking the English Japanese mix so far. I think for the garb they should use kimonos and yukatas or more informal clothing, but have English suits and dresses for more formal stuff. 

As for my ideas for the royal family. I think there should be more than one child, another prince or two, or maybe a princess. The Emperor should be the one in charge for this generation and he should be a fair ruler who is loved by the people. For the Empress I was thinking a bit along the lines of the Dragon Empress from Chinese history. Started out as a something lowly like a concubine or maid and worked her way up to Empress. So people may not have seen her as a worthy match at first, but she proved to them that she was in fact worthy by guiding her husband through some tough choices that only a woman would really know how to deal with.

That's all I've got so far.