IIRC, that’s how some forms of kiddie-porn were found to be legal in Japan. Since one of the laws was worded such that it was illegal to show pubic hair, but not illegal to photograph the pubic region of anyone who didn’t have hair. (I’m probably completely wrong about this. It’s not like researching kiddie porn is one of my hobbies, ya know?)
I did a Google search on “Japanese Sexual Mores” and came up with this letter which appears to be more anecdotal than scholarly, but I think it’s worth a look.
The information I mentioned but couldn’t cite from online was from a Washington Post article about Peter Greenaway and the film he made about this.