a) Which anim are you discussing?
b) often, in a "historical epic", a handful of characters will be peppered amongst a mass of "true" figures (ie plucked from reality) in order to create the story. That is, in a story about Napoleon the writer may stick in a single, important General (unnamed in history - fictional) amongst a host of true figures (Napoleon, Josephine etc) and use him as a generator of plot.