This cosplayer's outfit is certainly unique. It reminds me of a captain’s uniform in the Gundam series and a futuristic French maid of some sort. Maybe the fan she’s carrying holds some kind of clue to her identity?
The illustration of a girl behind her looks scarily intimidating as well… Anyone have a good guess? Thanks to Wendy for sending this in!
EDIT: Thanks to anon for letting me know she is Rindou Rina from Pastel Chime Continue!