Unfortunately, most of the Japanese population (maybe even more in most Western countries I know of) will be into exactly what you put in front of them. These days idol groups are very popular, in particular AKB48 and similar groups. Also, K-pop is very popular now, and ofcourse there's "anime music", though that's a very loose term...
However, there are sub groups in Japan too!
The hardcore rock/punk/melocore scene is pretty strong right now. And there's of course the Visual Kei community and heavy metal community (though they seem to mostly be into foreign music), and there's the hardcore techno/ravers scene, but I don't know much about them.
Traditional Japanese music is not generally popular with the kids now, but I'm sure there are interest groups for them too!