LogFAQs > #979372668

There was an anime film so fucked up Japan banned it. Custom confiscated and destroyed the tapes. It was also written, drawn, and animated by one man (its creator) because no studio would want anything to do with it. Here's a description from MAL:

As of the 2010s, the film was screened frequently throughout Asia and Europeespecially the latterbut never in the United States, due to import laws regarding certain types of pornography.

It is in some regards considered lost media and is also considered one of the most controversial anime due to being banned almost everywhere, including in Japan.