[jiryha]

Not really.

As for the key, I don't speak or read the language so this is a wild guess based on what i've seen in the two volumes, but she has a key and a 'keyhole' in place of her pussy, as do other characters, and multiple times she saves the day by 'unlocking' another girl. There's also a blond chick that seems to possess her to degrad her and usually saves her by extension. she's in the pages you posted (the one that steps on her head)