I'm wondering how Su Luxia took the place of the sacrifice without arousing suspicion.
I'm getting a similar vibe from the FL as I did back in the high school arc. She's ruthless and has no sense of morality whatsoever, she's introduced crossing the Moral Event Horizon while dealing with a Monster of the Week who was clearly in the right, and this seems to be deliberate.
It seems like she was supposed to improve as the story went on, but like those two, it's unlikely that she faced proper punishment for her vile actions at the start. With how her Master is being set up, there is room for the writer to shove the responsibility onto him because he's the one who taught her to be amoral.
We'll just have to wait and see what secrets Su Luxia uncovers. There's still something suspicious about how the System's infrastructure stumbled while inserting into the world. Did it somehow not realize this was a ghost story?