I always wondered . . . Does the protagonist Girl get raped or does she do it voluntarily?
It's kind of complicated, she gets spiritual power from sexual activity so being raped is technically to her advantage, and the kind of demons her clan fights are of a sexual nature and corrupt people sexually, making them intensely lustful to the point of removing inhibitions (mostly for women) and/or making them rapists (mostly men).
So for her, it usually works out, since she'll get raped by anyone who she somehow can't beat and in the process gain enough power to purify them.
However, it kind of curses her too to like the demons so she needs to have sex and is constantly distractedly horny. There's a story scene from when she was a kid and trying to run away from her clan, but her curse got so bad that she stopped fleeing to relieve herself and her clan just walked up and basically told her "ya this is exactly what we said would happen, you need to train to control yourself so you can properly use it as a weapon."
So now she kind of accepts it. It's definitely rape, but she also needs it and the corruption also spares her from worse fates like death or dismemberment. She does have a pretty cocky personality about it all but imo it's at best a defensive mechanism mixed with grudging acceptance.
What to really do, after all? But there's no indication she has a secret rape or CNC fetish or anything that specific. It's just the cards she was dealt and she literally has no other choice but to live with it.