Also I realized she can't be the girl who was watching them in the forest, because her heels' colours are different - in the previous chapter, we clearly see they're white, whereas here she's wearing black heels.
Honestly all the girls look the same because of the art style, so it's really hard to get any sort of recognizable detail from their faces and tell if any one of them is Tsubasa.
@abconline that's my guess too. With all the red flags the author is throwing around, people are bound to suspect it's probably this girl + someone else, but what if the plot twist is they're ALL working together? Not many would see that coming.