Through the years, I have watched the land of Gensokyo... I have studied, trained, exterminated within its barrier. And in time, I have tamed it... shaped it. Nowhere in this land have I met a youkai equal to myself...
Between "Sakuya hails from the clan of time-stopping vampires" and "Sakuya is a direct descendant of a Master Assassin", I'll definitely take the latter.