I have no idea who this one is either, but she's from Winter Comiket 2009, and she looks like a fighter to me. Maybe she's from a game I haven't played yet?
I have to admit though, her costume is really cute. I love the ribbon details on her outfit. Who knew you could string the ribbons on your stockings?
Guesses are definitely welcome! Oh, and in case you're wondering why I don't reply to emails lately, it's because I have too many contributions coming in! I will try to feature them all, so please be patient with me! Thank you for all the beautiful photos! Keep sending, and keep a look out for new posts on Cosplay Holic!
EDIT: Thanks to anon and Furei for commenting that this is Musubi from Sekirei!