Three out of four 13 to 18-year-old girls in middle and high schools have been solicited for sex, a survey in Tokyo found.
The figures reflect a growing trend of schoolgirl prostitution, or compensated dating (Enjo Kosai) as it is euphemistically known.
Though only a small group was polled, the results are significant say researchers, because Japan's school population tends to be so uniform in behaviour. A research group led by Yasuko Muramatsu, a professor of sociology at Tokyo Gakugei University, questioned 121 girls from around the city.
Fifty-eight per cent of the girls who had been approached said the men had offered to buy them presents; of these, 30 per cent were told they would receive gifts worth up to 50,000 yen (pound;250).
Japan has just passed a law prohibiting people from having sexual relations with under-18s for money. Previously, only local bye-laws barred adults from engaging in "obscene" acts with under-18s.