Upscale Gentemen's club in Roppongi Tokyo. They have a few Filipina bar girls, too, as Japanese men love to be around sexy girls from the Philippines who know how to sing a song along.
The best site for single male travelers. Lot's of reports and huge archives from Japanese brothels with plenty of pics and a message board with tons of articles, database of apartments and hotels.
VIP room in karaoke bars, massage brothel aka soaplands and escorts are the most commonly found forms of professional sex in Japan. The trade is influenced by traditions and culture. Foreigners (Gaijin) find it difficult to find their way to Japanese prostitutes.