As you are perhaps aware, Japanese law on pornography is ridiculously strict and (infamously) bans the display of genitalia.

Naturally, some silly law could never stop a bunch of horny guys and so they merrily distributed Urabon magazines on the Japanese black market in the '80s and '90s.
These sought-after artifacts from a bygone era feature erotic hardcore photography and (gasp!) actual penetration shots. Absolutely unheard of in times when genitalia had fewer pixels than your average Famicom sprite.

Thanks to the wonders of AI, you too can now generate your very own banned-in-Japan hardcore pornography! Just don't let the prefecture police catch you...