I have a similar question to ask. What are the anime censorship laws in the United States? There appears to be major culture difference between United States and Japan and I am not sure if that implies a difference between their respective anime censorship laws.
The FCC, the government body responsible for broadcasting media, does not have any specific laws against animation that comes from Japan, otherwise known as anime. Because the 1st amendment protects the Freedom of Expression, the censorship laws that are in place and enforced by the FCC in the U.S are concerned with obscenity, indecency, and profanity. The short summary of the law is that, for media to be prohibited to be aired on television from 6 a.m to 10 p.m, it must:
- Not be acceptable to the average person.
- Depict anything that violates other existing laws, such as child pornography.
- Lack any artistic, scientific, political, or literary values.
- Contain greatly offensive language or otherwise known as profanity.
This is arguably vague, but usually if it meets some of the criteria above, it would be permitted. For example, a satirical anime on U.S politics would probably not be acceptable to the average person and can be offensive. However, if it contains a good amount of political value in the work and does not violate any other existing laws, it would be permitted. Even lolicon material is permitted as it meets some of the criteria above, although it is a murky territory and can land you in legal trouble nonetheless.
Note that this is also the criteria used in courts for media in general, also known as the Miller Test.
Censorship are also in place for libel and slander, but it would be extremely difficult for anyone creating anime to be prosecuted for such things as it would have to lack any artistic, scientific, political, etc. values.
The censorship that you see in anime imported from Japan and translated into English are self-imposed. Different studios handles it differently. For example, the infamous 4Kids Corporation would blatantly westernize the anime it imports, replacing Japanese food with American food, removing highly emotional scenes, and much more. There are also non-governmental ratings made by independent organizations such as the MPAA and government imposed ratings such as the TV Parental Guideline. Theaters and TV stations would follow these ratings to show what is and what is not appropriate to show in what timeslot, in addition to the FCC rules described earlier. Keep in mind that these ratings have no legal weight. A TV-MA rated content can be shown at any time of the day and no one would be prosecuted for it. People would probably think less of your network and so TV stations follow these ratings to keep their audience, but it is not illegal to ignore the ratings.
In summary, as long as it passes the Miller Test, it should be legal.