It boils down to current translation of Article 175 of the Criminal Code of Japan, which restricts circulation of “profane” materials. So while there is no particular law requiring control, that is the Jav porn.
In 1957, a point of reference was set in light of a Japanese interpretation of DH Lawrence’s Lady Chatterley’s Lover. At the time, the Japanese Supreme Court decided that vulgarity was characterized as “superfluously sexually fortifying, which harms the typical sexual feeling of disgrace of conventional individuals, or is against great sexual good standards.”
Current understanding of that decision clearly implies genitalia is revolting, yet the various stuff you find in Japanese porn is most certainly not. Make of that what you will.
As others have noted however, benchmarks have changed throughout the years. While it was once viewed as revolting to demonstrate any pubic hair whatsoever, that is clearly changed.
There have been not very many captures for infringement of the law, however. In any case, there have been a few feelings, which implies Japan has lawful points of reference maintaining genitalia as obscene. In 2004, Yuji Suwa, the craftsman of the hentai manga arrangement, Misshitsu, was conveyed to trial for infringement of Article 175. He pled liable and maintained a strategic distance from imprison time, yet was fined ¥500,000. He attempted to speak to the Japanese Supreme Court utilizing the contention that more obscene material could be found on the Internet and that Article 175 abused the Japanese Constitution’s assurance of flexibility of articulation, yet the Court didn’t tune in. Rather, they expanded the fine to ¥1.5 million.
At that point in 2013, three individuals were captured for offering vulgar pictures with inadequate editing. Since Suwa’s case and this 2013 case, numerous craftsmen, distributers, and film studios have been more watchful about self-restriction to dodge profanity accusations and after the Suwa decision, a few book shops brought down their grown-ups just area.
The law may in the end change later on, yet nobody needs to be the one to run the hazard related with setting that point of reference.