Consider this: A pack of wild Touhous. Elegant, flying Youkais nearing your human home. Trampling your human lawn. Having a tea party with your human daughter. And you can't do shit since they're youkais. Reimu grabs your wife and fucks her with her miko stick.
The Touhous finally dominate your household. They watch graceful spellcard fights in the sky and you are forced to be their sex slave. Such is the downfall of Human.