So, Satori-samaThey slowly start going outThat's how it normally goes...That's only the case for humansNo
Youkais from the surface are also based on humansThey can start dating, marry and have children in the same yearHaven't you been slacking offThere's nothing but youkai who can live hundreds of years undergroundThen they can make children and have a weddingAs for the surface it's based on humansAnd their relations go awfully quickIt's not good if you ask me