I think she really might be Kamuo Ichihime!
The billion yen question is, which came first: ZUN's idea of Chimata Tenkyuu, or the cancelled first Shizuoka Reitaisai? I'm very much leaning towards the latter, as UM was released only in 2021... Well, they were about to hold a very special market right on Ichihime-sama's home turf...no wonder she wanted in.