http://www.asahi.com/obituaries/update/1106/001.html

Apparently, she died of luekemia, at the age of 38.

I actually spent about 3 weeks on a movie set with her, about 18 years
ago. I remember her as being pretty, extremely skinny, and having almost
no personality; her manager (who might have been her mother: I never
got that straight) controlled almost everything she did. But unlike
most other idol singers, she could really sing. One of the few
J-Pop songs I still like is "Hurricane". A really good voice, and
when she was singing, she had a completely different personality. 

I always kinda wondered what happened to her; I guess sometimes it's
better not to find out.

Mike