I like the Pillows, first heard them on FLCL. They remind me of Oasis, yet I don't feel as ashamed listening to them as I would listening to Oasis, as a man (no offense, that's just me).
I like Soichi Terada's DnB stuff, Sumo Jungle is a good album.
I haven't heard much else when it comes to J-music. The only other arist I can remember is Deco*27. Some songs are alright but it's like, meh. I usually don't listen to this sort of music.