Yes (namely of Prince Shōtoku AKA Toyosatomimi no Miko), and no but Tojiko's possibly-stepmother - both the historical figures and how much they draw on those are kinda fuzzy. But then they're also 6th-7th century Japanese aristocrats who had a pretty different take on a Hell of a lot of things - case in point, Prince Shōtoku's parents were half-siblings...
To speak nothing of what the whole death and revival/undeath (respectively) business might have done to their perspectives.
I'll admit, I never really figured out the relatonship between Seija, Tojiko, Futo, Miko, and Hijiri. That whole aspect of Japanese culture is just totally opaque to me.
...I'd say that has rather less to do with "Japanese culture" than "ZUN being ZUN", ie. maddeningly vague just because he can (and cuz it leaves the fans leeway to fill in the blanks as they wish). Plus Seiga's Chinese anyway :U