No, MacArthur actually relaxed censorship laws.
In Japan, under Article 175 of the Criminal Code of Japan people who sell or distribute obscene materials can be punished by fines or imprisonment. Article 175 was included in the original document in 1907 and remains relatively unchanged.. Finding a workable definition for obscene has sparked much controversy over the last century. It is not uncommon for pictorial magazines to depict nude women with their genitalia airbrushed over in black, and video pornography routinely depicts explicit sex scenes with the participants' genitalia obscured by mosaics. Until the 1990s, the entire pubic region, including hair, was deemed obscene and unpublishable.