They've only had two appearances. Nagatoro didn't show her dere side for several chapters either. I imagine those two will be a bit more fleshed out in later chapters. After all, they haven't even been introduced by name yet. Long Hair gyaru is clearly aware of Nagatoro's crush but is more sadistic. Pigtail gyaru just comes off as a sheep follower of both Long Hair and Nagatoro.
My forecast is Long Hair is either the protective friend deeming Senpai as unworthy or rival to Nagatoro for Senpai's affections to get her to step it up. Pigtails is...well....comic relief. I'd give Pigtails the love rival role, but she doesn't seem like she'd be good at rivaling Nagatoro on ANYTHING.
Then again, I'm dreaming. I just really want to see a chapter where Nagatoro realizes Senpai is attractive to other women to see how she'd react to competition. After seeing the chapter in the Doujin where she faked having a boyfriend, I want to see the tables turned on her in that scenario.