The first national estimate of the virgin in Japan discovered an increasing rate of young adults with no history of heterosexual vaginal intercourse. After a comprehensive study of national fertility survey data, the University of Tokyo's public health experts came to understand trends in sexual experience over the past three decades.

The leader of the research who is also an expert in epidemiology and public health, Dr. Peter Ueda, talked on the previous news reports about virginity rates among Japanese young adults as being sensationalist and only included people that are never married and there was nothing about distinguishing virginity rates by age group.

With the recent analysis, there is an estimation of the whole Japanese population, more with a clear definition of the age and socioeconomic status of people that have never had heterosexual intercourse and compared trends over time.

From 1992 to 2015, there is an increase of 21.7 percent to 24.6 percent of heterosexual inexperience in women aged 18 to 39. And it was between 20 percent to 25.8 percent for men. After breaking down the numbers to smaller ranges, there was also an observation of the trend towards increased virginity rates even among adults in their 30s.

In 1992, only 5.5 percent of men and 4 percent of women between the ages of 35 to 39 reported no heterosexual experience. But the number jumped to 12.7 percent of men and 11.9 percent of women in 2015.

The National Fertility Survey of Japan collected the data as the Japanese National Institute of Population and Social Security Research implemented and designed it every five years. Using the data from seven surveys conducted between 1987 and 2015, the researchers included between 11,553 and 17,859 adults between the ages of 18 to 39.

The first author of the study, Cyrus Ghaznavi posited that the discussion around the effect and cause might become very complicated when considering who becomes sexually experienced and who remains a virgin, but heterosexual inexperience is at least partly a socioeconomic problem for men.

With the speculation from the research, women were more likely to have had intercourse if they had lower personal incomes since married women are more likely to have had sex and be full-time homemakers without a salary.

Comparing surveys in the U.S., U.K., and Australia, heterosexual inexperience rates in adults around or in their 30s is around 1 to 5 percent. Also, there was no data about the same-sex experience since Japan doesn't yet have marriage equality for same-sex couples.

People who have had intercourse in the past and since become sexually inactive are also relevant to the national fertility rate and public health implications, but the survey did not investigate them.