I have little patience for "love rivals" that exist only to cause faux drama for the main couple, but I don't think that's the goal here. This series is too kind-hearted to make this girl any sort of long-term annoyance. Heck, at first she wasn't even going to say anything and then she was willing to drop it until Takada backed out instead. I think it's pretty obvious that she's ultimately going to become Nishimura's first female friend. It'll take a few chapters, but I'm pretty confident that's how things will go between them.