Here's an article about Japan's Sex Volunteer Corps; an organization devoted to providing sex to Japanese women in sexless marriages. There are even a lot of cases of married Japanese women who are virgins:
Kim adds that members of his Corps have also solved another problem - that of an increasing number of middle-aged married women who're still virgins.
"Most of them have been career-oriented types who've submerged their femininity to try and compete on a level footing with men. But there're also a lot of married women who were virgins when they wed, usually to husbands who had also never experienced sex before, and then they simply lost the chance to ever make love together and the years went by," Kim tells Asahi Geino.
I think this phenomenon is indicative of the lower average sex drive of Japanese men. This isn't a problem you hear about much in the United States, but all Japanese women know about the problem of husbands who allegedly don't have time to have sex because they are too busy working. I don't buy that explanation at all. The typical young horny male is never too busy too have sex.