I thought it was an extension of gyaru
apparently, they are called landmine girls, because like a landmine there is a part of her that is hard to spot and when pressed causes her to explode.
To me, the jirai-kei fashion style feels like a more modern evolution of the gothic lolita's frilly dresses. The dresses became much shorter, but gained more ribbons in exchange.
But yeah, you're spot on about the landmine girl part. The stereotype is all about them being girly, sweet and innocent looking at first glance, but if you accidentally hit a nerve, or hell, just get involved, they could blow up on you and end up making more trouble than it's worth dealing with.
There's a funny quote out there from a certain vtuber that said, if a girl is wearing more than two ribbons at once, she's a landmine girl for sure. It's unfortunate that we don't have the protag's inner thoughts visible here, but I'm pretty sure he's dipping now because he knows the stereotype.