I am feeling increasingly bad for Seri. It doesn't look like she's folding under pressure; it looks like she's scared. And it's only in the aftermath when she's around Oogami that her anger and frustration takes the forefront. That or she's putting up a front in front of him. Chapter 2(?) established that she's almost entirely bark and actually just as nervous in spite of her behavior. I'm starting to wonder if this behavior of hers is a coping mechanism, recontextualizing the harassment as something she has control over and reasserting her agency. It might sound crazy, but that is how some people process their traumatic experiences.
Unrelated, it's nice to see someone who appears to be actually normal. The larger school body seems to be a bunch of psychotic horn dogs, and even while our MCs acknowledge just how ridiculous everyone else is being they're also pretty off-kilter themselves. Hopefully this girl ends up being a source of positivity and levity amidst all the tension and building drama.
.....Something's gonna happen to absolutely break her, innit?