So, not sure if I'm getting this right from the roadmap, but does this mean the final Harem candidate wont come up until after the final battle? Gonna be a loooong wait for the last girl (still curious why Xestris is considered in the Harem despite having shown no such inclinations).
Considering the last missing option is in the "Other" category, that means NPC Goddess/Demon, but I can't see who it would be, does anybody else have any ideas? Apparently it's a super obscure character that's been referred to earlier, but nobody has guessed it yet (which sadly means Vhala is a definite never added to Harem at this point....also rules out Ulrissa).
My guess is the introduction of the Player as an outside entity/observer, or a manifestation of the Tower itself. Maybe even go mad and throw Sierra in as an observer, or maybe something to do with the ongoing Broom Joke.