She's done quite a number of theme songs and major voice roles in assorted anime series. It's debatable whether she's done anything much that could be classified as J-Pop.
Assorted anime theme song recommendations:
- Give a reason (the Slayers Next OP)
- EXTRICATION (the Lost Universe ED. The normal mix of this is pretty good, featuring such oddities as a synth flute solo followed immediately by an electric guitar solo, and the chorus, which has a bit of multilingual word play. The Freaking Lounge mix isn't very good, but the P.G.F. Mix (by Poison Girlfriend) brings a really different sound to the song, with a high dosage of violin, drums, and bass... as such, the vocals aren't emphasized quite as much.)
- Just be conscious (the Slayers movie 'R' ED)
- RUN ALL THE WAY (a Slayers movie 'R' image song)
- Nemurenai yoru wa ("Sleepless nights"; a Slayers image song)
- I believe she did a version of Cruel Angel's Thesis (the NeonGenesisEvangelion OP)
- Successful Mission (the Saber Marionette J OP)
- Lively Motion (the Saber Marionette J to X ED, I believe)