None that I know of. All of her history has been with See-Saw.
Her vocals really gel well with Kajiura's compostions, much like Maaya Sakamoto with Yoko Kanno, but Maaya's albums are usually released under her name only unlike as a band name, though Kanno is well known in her own right. See-Saw was around before Kajiura and Ishikawa joined and they now remain the only two.
I wouldn't bypass the possibility of her Ishikawa coming out her with her own solo projects, but for now she is involved in other ventures and of course her role as lead vocalist of the band.