Another good resource is the Japan Subculture Research Center by Jake Adelstein (American journalist who spent 12 years in Japan on the crime beat for the Yomiuri Shinbun).
PS. Off-topic, but calling Stross a "pop-sci-fi author" is an injustice! Kevin Anderson and Orson Scott Card are pop-sci-fi authors. Stross writes hard science fiction.
Sample post: the yakuza's role in relief efforts -- http://www.japansubculture.com/2011/03/the-worst-of-times-ca...
PS. Off-topic, but calling Stross a "pop-sci-fi author" is an injustice! Kevin Anderson and Orson Scott Card are pop-sci-fi authors. Stross writes hard science fiction.