I might have misread somewhere, but I was always under the impression that event girls have a slight priority over troll girls when dropping. Does anyone know if that's the case?
I guess I'm just getting super unlucky...I haven't had a troll girl drop in about a month now and instead of Bunny dropping I've gotten the two girls I never finished getting from Donatien instead of Bunny. Feelsbadman.
Edit - literally just got her 4 attacks after Kelina dropped. I've got little to no Kobans left, but 3 girls - not too bad, I guess.