In a somewhat serious attempt to get this back on topic: Black socks are uncommon and red socks may even be downright rare. Why is this relevant?
On an off chance, I had paid attention to the character's feet before and while it's hard to tell from
the in game imagery since the feet are, as previously mentioned, rather quite small. Still to me it kinda looks like Rumia's probably wearing shoes. Red high heels to be specific, since her feet are kinda pointy.
If she is, where did those shoes come from? Obviously, like everything else in the world, they must have been made in China. The only other character visibly wearing shoes on that same sprite sheet looks to be like Hong Meiling, the scarlet devil mansion gate guard. Perhaps it's possible on her way out, Meiling gives Flandre a pair of her shoes out of concern that the decorative silk socks will become dirty and worn out, if left unprotected and exposed to the elements of the great outdoors. Naturally, this being a Scarlet sister, Meling lent out her very best pair. (Few other people wear shoes at this point because coming from the outside world, they are quite rare and valuable but since socks often seem to be lost in between the gaps quite often, it's possible Yukari has more socks than she knows what to do with and gives them away freely...)
Either that or Rumia's not wearing shoes per se but Ruby Slippers because she's Dorothy from Kansas/Oz. It wouldd explain why she got in a fight with the local witch; gotta finish off the last of the wicked witches, as designated by the black pointy hat. I mean hey, why not? It's not that outlandish a possibility, considering that we have Alice from Wonderland. The darkness surrounding her could even be the interdimensional tornado responsible for landing here.
