I'm not sure how to lose to Herba if you don't even fight her, because once the game ends, you can't continue the game, it's game over. I also don't know how to unlock other characters, if any?
There are only 2 characters in the current version, Herba and Alice. Herba's scenes are all acquired by purchasing her tickets and redeeming them. The only exceptions are as follows:
1)When you accumulate IOUs (little documents in the inventory), you can tell Herba you won't pay them. She says she will forgive 1 debt if you can endure her hands/feet long enough. There are two scenes, 1 for hands, 1 for feet.
2)There are occasional scenes that you get when you enter Herba's cave. I'm not sure the exact progression trigger, but I think it has to do with how many debts you acquire. Just keep leaving the cave through the door and coming back. When the scenes are available, she won't be standing at her store.
3) Once you have 5 debts, Herba will force you into an ultimatum. Either become her slave, or she'll tie you up and whip you. Refusing her offer of slavery leads to a very short BDSM scene that also reduces your IOUs by 1.
4) If you accept Herba's offer to become her slave, there are 3 scenes that happen in order. 1 is the signing of the contract, 2 is where herba rapes you, and 3 is where she makes you service her. Credits play at some point in between these so just wait through them to see the rest.
As far as I'm aware, the "Game Over" for Herba isn't actually a game over. I got the screen, but it just let me keep playing as if it didn't happen.