FJH said: Between Suika and Remilia is Tokiko. I want to say Mystia for Ms. Purple Hair, but asides from the ears, the other elements aren't common to her.
I think it's more likely to be the youkai from touhou reireimu (osana reimu sequel) It doesn't really have a name though...
It just struck me: Who's that on Reimu's shoulder? I thought it was Rumia at first, but she's nibbling Reimu's thumb. Comparing the tag list to the image, there doesn't seem to be a character tag for the girl on the shoulder.
Also, Remilia's unbridled display of affection amuses me.
Seeing the Hakurei Miko is there with a mask, I'm thinking this is probably based on the Osana Reimu universe, so the person on Reimu's shoulder should be Rumia before she got sealed.