Actually, the japanese law is that way because at Japan's surrender in WW2, General MacArthur insisted on there being a "no visual depiction of genitalia" clause in their new constitution.
comment #50768 You are incorrect. The current censorship laws date back to the constitution of 1889. Article 175 is the part which forbids the production, distribution, and publishing of material which can be deemed as being "injurious to public morals."
(This is the MacArthur claim Anonymous) Really, Motojin, I didn't know that. I had only learned the Macarthur thing from one of those "Why does this woman have no vagina?" PSAs at the start of some of my hentai vids :P Anyway, I don't suppose there's a link or something you can give me to read up on article 175 of the 1889 constitution?