Ok then, somehow I managed to find how they are called (in order to give myself a hint on what to do) , and they seem to be related to some count (either prostitution as mentioned earlier or maybe something else).
They are called "Cum-filled Dumpster", "Well-used Dumpster" and "Disgraced Slut".
But yeah if it's a bug, there is nothing I can do.
3h lost yesterday trying to get them.
Here's a small review from me though:
In general after playing the game and managing to 100% the game, I can say it's worth it if you are looking for a fast (2-3h) and classic hentai-jrpg experience.
The game has no difficulty though, because it's really easy to overlevel, and in nympho mode, every enemy "grab to rape" results in it's own death. As well as it's really easy to get out and in this state, since money is so easy to grind (made 100% completion really easy that way though).
Bosses are killed by doing a few mana attacks and they don't try to rape you mid-battle but you get the typical H-defeat-cutscene from them as in many other games.
Story is a berserk parody, but is entertaining enough for a H-game (at least I was not bored to death). Just be aware (because I was confused at first) that if her armor breaks (not the same as removed), she becomes pure again and suddenly is not open to sex, explaining why her demeanor is always the same in defeat-cutscenes.
All in all it's a game with no replayability, once you're done with the story, you can do some few things post-game, but not really worth it imo (better just unlock the gallery at this point).
Last thing:
DO NOT WASTE 3H TRYING TO GET THE LAST TITLES BY DOING THE BROTHEL OVER AND OVER AGAIN.
That bug really screw me over.