The only two new characters they've introduced (admittedly, I've only seen the first) is the hot black dean of SFT, and Obake.
Not sure Hiro even knows Obake exists and just thinks it's all Yama.
As a side note, I wonder if we'll be running down a list of Japanese monster themed big bads.
Can't wait for Oni to show up.
I also wonder, if they do a 'Yurei' if they'll stick with the mythology or acknowledge it as part of her origins and she's a jilted lover.