Thanks, Hong. Now that's your've mentioned it., I've heard Birthright referred to on the boards here before. Just to be safe I did a little research on the setting by checking webpages devoted to it.
Paka, I guess it depends on what you want to do. I see no trouible with some modification of bloodlines. The leaders of the seven clans, and the Hantei are all decended from the original eight Kami that founded the Empire. And the idea of people running a clan, or family, could have appeal.
On the other hand, except for a one shot, it's very hard to imagine Hantei the XXXIX, undisputed Lord of the Emerald Empire, and his vassel, Daimyo of the Lion and warleader of 300,000 samurai, off on adventures by themselves. If nothing else they'd be badly neglecting their roles as leaders.