I'm currently on floor 3 now. Overall a nice game, encountered bugs here and there but nothing game breaking yet. Still i haven't come sccross any lockpick or anyone who could picklock yet while there're some chest and locked doors around.
Viewing post in Blueberries chest and the Beginnings town's innkeeper
The class girls are temporary party members, for special missions/events.
Your basic (potential) romances in each playthrough are:
-Hana
-Bloodfang
-Hachi (you'll meet her later)
-Your class girl.
There are also other romancable characters, but they do not become party members at any point.
Edit: As for Nao, you have already met her again, on floor 3. She was the girl who was being beaten by the villagers in Blackcry. If you were an assassin, you could have fought them off.
I don't know what i've done wrong but it looks like Hana has a thing for Bloodfang more than my character lol even tho i've been treating her nicely. Not sure i've done anything that offend her unless giving tips to the dancer and walked into the brothel asking about girl without doing anything pissed her off lol. Are the npcs able to romance each other in this game? Sorry for asking too many questions but i find your game intriguing despise some bugs.
If characters get annoyed with something you do, they will comment on it, so don't worry about secret parameters. As for Hana, at the start she is just nice to Bloodfang, same way he is with you. The NPCs can have relationships with each other, though that depends on your actions. Particularly, if you do missions with the other girls, or if you romance Hachi enough, Hana will be in a relationship with Bloodfang.
Keep in mind Hana (specifically her) is not monogamic. Even if you romance her to the max, she will still occasionally flirt with other characters (more often than not to your advantage). You will understand her character better as you go through the game.