At this point, with a lot of people not yet having chosen characters, I'd guess that this is going to turn out less than 50% anime characters.
Which number is high because I became so interested in playing my two anime characters.
Which is ironic because if I had not been interested in Keiichi/Belldandy, I would probably feel lost in a game with too many anime characters myself because I also haven't seen much of that. Too many powers, too many nuances and sometimes hard to relate to. I'd say if Ah! My Goddess had been more like a Shonen anime, I probably would never have taken to them.
Maybe it will help if I explain the two then. Keiichi is a normal guy. So far, the most normal guy anybody has even openly thought about playing here. He's normal, and he's nice, and weird things happen to him. That's his thing. if I write him well, then he's probably the easiest guy to understand in the game.
Belldandy is meant to be a bit alien, to everybody. To normal mortals, to Keiichi, to other goddesses like her, even to her own sisters. Her own anime doesn't even quite seem to understand her in some ways, and she's very extremely the way she is. Which is also well described by "nice". So to a certain extent, nobody is supposed to have too much familiarity.
So those two look like they are going to be somewhere around half the anime characters in the game. Hope that helps.