She's an interesting villain. From the moment we meet her in chapter 11, she has this half-medical half-narcissistic detachment that leads her to see everyone as experimental subjects. I wonder ... when she found out there were humans who could naturally see, if that catalyzed a crisis in her worldview that could only be rectified by reimagining herself as something more than merely human. And so she swallows the adult form of the kobutori parasite, making her into a predator of humans already infected with it (or in terms of the mythology from the town, a deity of sorts).
Then here, we see her use that specimen to ... steal expensive jewellery? That pettiness, it seems at odds with her earlier ambitions, with her talk about gods and immortality. I think there's something interesting here. I have some notes sketched out, basic thesis being re: the fundamental tension of scientific study of human societies is that controlled experiments require you to distance yourself from the object of study, but social/interpersonal phenomena can only be understood from the interior perspective - via immersion. Note that all of the scientists studying this town wear headphones. She's the only one who's taken that next step. I feel like this is a promising angle for understanding her character but I think I'll wait for the next chapter before committing to anything.