Historically, Prince Shoutoku Taishi lived from 574-622 AD and united Japan under the centralized government of an emperor. Known by his real name in the manga, Umayado, he is a cold and calculating politician and mystic that uses his beauty and cunning intellect to manipulate those around him. Umayado's only weakness is Emishi, the son of a rich family who Umayado finds himself hopelessly attracted to.

(Source: Anime News Network)