I followed J-pop quite a bit when I was in college, but I don't listen to it as much these days. I was a big fan of Tetsuya Komuro and his assorted acts (Globe, TRF, Tomomi Kahala, Ami Suzuki, Namie Amuro, and TMN, just to name a few) when they were still at the top of the charts. TK, as he is known, pioneered a style in Japan that blended European techno/dance music with traditional pop sentimentality. He was enormously successful, but didn't adapt well to the changing times, faltering when R&B sounds became popular in the late 90s, and being upstaged by Tsunku's Hello!Project, whose appeal was brilliantly manufactured to resonate with consumers in post-Bubble Japan.
The article linked to below is from the Guardian Unlimited (August 2005; a bit old, but still interesting if you haven't read it). It talks about Hello!Project's success, its fanbase, and Tsunku, the man behind it all. The article also discusses the enigmatic Johnny Kitagawa, the man behind SMAP and so many other boy bands. Kitagawa has been a major player on the J-pop scene since the 60s.
Here's an article on TK from many years back that James wrote:
When will the next king or queen of J-pop emerge, I wonder?