Two Nagisas were accidentally combined into one, so the artist dissident93 meant is now here:
http://vgmdb.net/artist/14582.
I couldn't find a homepage/blog/etc. for the singer NAGISA who worked on those doujin albums so I don't know if she's the same person, but the casing of her name is different than the one who sang for jubeat ripples (NAGISA vs. Nagisa).