1st one is a bird-girl, u need to use the brothel one or two, then go to the 2nd upper city (where u recieve ur cat-catching Q). The soldier girl will give u a Q to find her (the place is at the right corner of the 1st mountain site)
2nd. this one required u to have 1 or more Dark magic stones in hand. You will encounter a red field boss at the Stone magic circle after u have to go round to access to グヨ卵鞘/管理区. As I said it required u to have Dark magic stone, or else, the field boss won't appear. After interact with the boss, u will have a conversation w a clown girl. She will ask u for 1 stone, if u agree to give her, u will turn back, and everytime like that, cost one stone :)) - But if u refused, u will enter an area to go around then fight her.... I recommend u do this w hp cheat or later gameplay cuz they are beeping strong for the 1st game play. And when u won, u can take back ur stones, if u gave her some :v And 1 more stone at the stone magic circle. Check the brothel and u will see her there.
3rd one, the angel girl at solo arena (who u can see eyes :v )... i dont know exactly how to make her appear in the brothel, just around chapter 5 or 6, after fighting her and win. Before that, she will just appear for u to fight all over again.
There are 2 scenes with the brothel owner. 1st one is after u enjoy the basic 2 girls, 6 times per girl (until they are free). 2nd is after u found 2 more girls.
I guess thats all for the 1st brothel :3