Thank you Fei for the welcome :)
This site has been one of my favorite.
Excellent suggestions guys, all the games you recommend have very good reviews.
I will definitely check them out once I am done with Fate/Extra (currently playing).
Radiant Historia - three of your requirements. AMAZING RPG, definately worth a try if you can get it still. Doesn't do J-Pop tho.
I totally agree, its my favorite RPG on DS, too bad its a bit underrated and many ppl dont know about it.
An all J-Pop soundtrack is pretty much going to be limited to P3, P4, or TWEWY.
(Also I'd argue that P3's soundtrack's influences were broader than just JPop. The battle themes have a major highlife feel, and there's still a lot of the minimalist ambient, smooth jazz, and krautrock from the other PS2 megaten games).
True, maybe me saying J-POP was a bit of a stretch.
You do put it in a better terms, that is kinda what I liked regarding the music in those games.