Damn. Here's my take: MC saw tall girl's age on that form and realizes she's way younger than her, MC then says 'pervert' in reference to herself.
Edit: Ha guess we're all thinking the same thing lol. Makes sense that MC would judge herself harshly since she apparently fights the perverts in town but I don't think tall girl is a minor, so it ain't that.
Yes, kind of like that.
One main character is a really eccentric numbers head, who has a habit of going into sudden emotional panic and just saying what is running in her mind out loud, without context and no regard to whomever might be listening. She's a veritable misunderstanding generator.
Other one is a traumatized girl, who has faced hostility over her homosexuality by her family and probably in other instances too. So she is tuned to interpret anything unclear regarding herself negatively.
I think it's just really on the nose contextually that there are "bumps on the road", probably a lot of them.