She has some resemblance with Nagi from Kannagi. It may be a coincidence, but a quick lookup showed that Seitokai Yakuindomo's animators, GoHands, have done sone 2nd Key animation for Kannagi as well.
Although for tagging purposes, I guess we can tag her as SYD_ED_Girl I guess, seeing that's her only appearance. In fact... *adds said tag*.