I think this week will be pretty easy for those who are familiar with online games.
My guess is that she’s from Ragnarok. But it’s been years since I last played the game, so I’m no longer that updated when it comes to character looks and such.
This could also mean that I’m lazy or something of the like to look for information regarding this cosplay. Haha!
EDIT: Thanks to Fairlady-Z for letting me know this is Ragnarok Online’s Assassin Cross!