She’s a cute, red-haired, bishoujo, but with only a portrait shot like this, she could probably be anyone! I’d have better lucky identifying that character behind her (who’s either Kyon or Koizumi Itsuki from The Melancholy of Suzumiya Haruhi)!
But I’m sure you guys know better than I do. So please leave a comment if you know who she might be! Thanks again to Fumiki for sending this in!
EDIT: Thanks to anon for letting me know this is Rio Rollins Tachibana from Rio: Rainbow Gate!