How do you unlock Erika? I've unlocked every other character, have got at least one end for all of them other than Chloe and Katherine, and the heart amount is blocked? Is there a particular requirement in some plot or is it just a really high amount of hearts?
I think there may be a bug in obtaining her, then. I started playing in one of the older versions and never obtained her, nor did she ever appear in the shop despite me owning the Hostess Club. Currently on the most modern version for Itch and her name is still greyed out "???" and her purple heart on the app is ?.