Now, I'm as equally surprised as most P4 fans/players are (or should be), as I myself have never seen this character before until 2ch (surprisingly as always) actually spotted her in the show, before picking up this topic and investigating further.
website has listed her down among the minor characters; Nakamura Aika (doesn't she remind you of Metis?).
Here's a little description of the above.
A long time classmate and daughter of the Chinese Restaurant "Aiya" in Inaba Central Shopping District.
(The one with the 3,000yen ramen that gives you random parameters. I love that store).
Usually helping out at the restaurant, although silent most of the time, she gives the impression of a professional with thoroughness while in the store.
Her latest service to begin is catering.
On top of that, Yuuki Aoi (CV:悠木碧), will be voicing the new character!
So there you have it, suddenly a new character. I hope she's not another victim and doesn't severely change the plot which happens to be following the adaptation very well at the moment with lovely soundtrack from the game (god bless you, Meguro Shoji) and Personas manifesting magnificently.
Where 2ch managed to spot her in Episode 1 itself.
(T'was too busy concentrating on Yosuke's lovely ass which was raped by Chie)
Persona 4 airs every Friday at 1.30AM JPT on MBS during the Autumn 2011 anime season.