>>527947563
Probably Elegg in Nikke or Kotori in BA, but the progenitor is idolmaster CG's Kanako, who I think has always been pretty well-liked. There's also quite a few other colleagues of hers on the soft side who, while not as popular, got a fair bit of exposure by association and did develop their own small fan pockets.
My theory is that, given CG's been around for some 13-14 years, some fans back in the day could have grown up to get into game development recently and pitched some more inspired design concepts.