I used to be in with the NYC Japanese businessman scene. We used to hit the karaoke hostess places in the East 50s every week. Once they got their drink on and got all hot and bothered by the Japanese girls there, these guys used to head down to Chinatown to get their rocks off at the Chinese/Korean places. When I asked about real Japanese action, they always said it was all Korean and Chinese.
In fact, these guys would take out the Japanese hostesses from the karaoke places, spending thousands over a period of months on dinners and drinks, and get nothing out of it for the most part. It was kinda sad, actually, as they were thrilled when I introduced them to the magic of the Harmony (yes, this was a while ago).
The little real Japanese incall they saw was very UTR, word-of-mouth, with 2 or 3 college girls working out of their apartment, seeing very few (and only Japanese) guys on a part-time basis.
I never partook.