A new gem that dug out recently. Apparently, she is cosplaying an original character which means the costume is totally unrelated to any works. However, her dark bunny open clothes concept does resemble a certain character I know. Black Rock Shooter?
Thanks to an Anon, we can now identify her cosplay ideas are from a Supercell character as Darth Wooser. Not a popular character in the field but was taken a back that the music group got such a mascot. Anyway, great cosplay from our lovely Ms. Tachibana.