First google responded with these
http://www.dazereader.com/schoolgirlprostitutes.htm
"Wai Wai runs another article about Japanese schoolgirl prostitutes, who hook up with clients through online personals sites. "About the only way for a junior high schoolgirl to make money is to sell sex. Our school doesn't let us have part-time jobs, so we do this (sell sex) once a week or so and that makes us enough dough. If you're a junior high schoolgirl, you can say you're a virgin and sell your virginity for a high price. I got 350,000 yen [approximately US$3000] for my virginity once. The guy was some sicko of about 40 who said he ran his own company. I've sold my virginity three times so far." (Jun 2002)"
After some digging for the bad stuff I did find this
http://www.thaipro.com/news_00/146_t...utes_japan.htm
More than 30,000 Thai women have been tricked by the Japanese Yakuza maffia to work as prostitutes in Japan, a senior official of Thailand's Ministry of Social Development and Human Security has revealed
So there is some bad shit in Japan, I am not going to say all the girls are greedy high schoolers, or girls pretending to be such. But I am saying that many of these girls are just normal people with a strange little part time job.