But seems like a couple of years ago that J-girls started showing up with some frequency is clearly established agencies. A while back, 6 months? a year? forget the timing but was talking with one of the girls. She said there was an agent in Japan that was working with both sides -- Japan and the US. Sounds like someone has put some logistics together for the J-girls that solves a lot of their "how to do this" problems. Particularly as most of the J-girls seem to have much poorer English language skills than the K-Girls. The exchange rate has not been hurting either but not sure how much that actually figures into their decision making.
I don't know if Japanese also enjoyed the same visa waiver program options Koreans do (would think so but histories are different so political relationships might differ also. I did notice the following:
"Japanese travelers who plan to travel to the United States for tourism, business, or transit purposes can apply for the US ESTA (also known as the Electronic System for Travel Authorization).
This allows visitors from Japan to avoid the longer, more complicated visa application process at a diplomatic mission. The ESTA can be obtained online at the traveler’s convenience.
To obtain the ESTA, applicants must meet a few requirements and fill out an online application."
If the ESTA is fairly new for and simplifying their travel authorization process might also explain why we're seeing the influx.
I will say that your description of YEMV sounds a lot like I was here, and led me to pass on seeing more of them. A 20% success rate is not what I am looking for