I met with a Japanese woman for quite a long time and asked her about this, says that many shave and do not shave is a relic of the past, young people do as they want.
It is believed that shaved genitals are a sign of debauchery, as it is usually done so that the hair does not interfere during sex. Not only among women, but also among men, this began to be considered a sign of bad taste and low human culture. And for a country in which there is a developed system of public baths (and sometimes a combined male and female), in which families / friends / colleagues often come, this has become something of a stigma that may not leave a very pleasant impression on friends and acquaintances. But this does not mean that dense vegetation is welcome, if it greatly interferes with it, they can trim it.
There is a video on this topic from a girl who sometimes lives in Japan for work: https://www.youtube.com/watch?v=6zCuXKJsr5E&nohtml5=False
Well, for those who are too lazy look, earlier in Japan it was believed that girls of easy virtue and those who live an active sex life, if only for a short time, shave their pubic hair.
In Japan, there is a law prohibiting showing openly genitals, and therefore, basically, in porn, all the most interesting is hidden by a mosaic, and vice versa - dense thickets give more space to the operators of porn films. Hence the reverse mapping on the consciousness of the masses. Japanese youth fuck in Love Hotels, and there it is Japanese porn that is channeled on all channels. And in every video distribution there are at least several hundred porn DVDs. Thus, there is an identification of hairiness and sexuality.