If I remember correctly you need to be 2 times first place, 2 times 2nd place and 2 times last place with the dayly contributions (=6 different scenes).
To get first place you need to pay about 50 k for 2nd it was something about 40k.
the worst thing is that you need to earn at least 30k per day and if you don't pay up the debt just increases...-.-
Also there are a few other events (I'm not too sure wheather they influence the event line):
The orange haired guy mentions something about how he likes braided hair -> you can ask Dorothy (redhead in the arena to do it for you) -> you can earn some extra cash from whoring to the guard [about 3 different scenes] (can also do it for free [about 3 different scenes]) -> ask the owner of the whorehouse to teach you -> the green haired girl wants to talk to you outside the arena (not sure what is triggering this but my guess is after she get first time last place with the dayly contributions you just need to go and leave the arena).
If you have seen all these events it should be a matter of wasting a few days until the main event triggers where you will be asked wheather you bear the magic of the elf. If you choose not to, it leads to you both leaving torres for the elven village (with a quite absurd difficult fight to win to enter without a bad end).
As far as I know there is only a bit of interaction with the Lamia sisters once you go for the relic questline. If you defeat them than that's it, if you are defeated you can choose to flee with help (further plotline is under construction - something like slime transformation is my guess). If you stay you get the Lamia transformation and can leave. Losing a 2nd time gives a bad end and returning after getting Lamia transform also.
As far as I know there ins't any more contet with Lamias in the game.
Use
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-> drag your safe file into the page, scroll down and press "File unpack" than use search (most browser support Ctrl+F) or look yourself for the word "shame". You will find a block of parameters and "reason": (the one directly below shame) is the parameter for sanity.