/jp/ - Otaku Culture

Shingyoku, besides being the Hakurei god(s), were also the first Hakureis. The human male priest marries the female Youkai and produced humans with the Youkai's potent magic. This could explain Reimu's natural talent. They probably gave birth to half youkai like Rinnosuke but lost their immortality as their descendants mated with normal humans until their youkai blood is all but gone. The only Youkai characteristics that remain are the Hakurei's immense magical prowess. On the other hand, if their immortality hadn't gone away and they died mostly due to battles, this could explain why Reimu is still alive at the end of Shuusou Gyoku.