The ban on the import and distribution of Japanese media in South Korea has had a long history since the founding of South Korea itself.
The origins of such censorship date back to the very first Independence Day of South Korea on August 15, 1945, when Koreans were freed from the Japanese. On that same day, the Law For Punishing Anti-National Deeds was enacted. Its intent was mainly targeted at Japanese media, resulting in Koreans having no legal access to any manga, anime, video games, music and movies from that country. The ban took effect throughout most of the last two decades of the 20th century. By the mid-1960s, after the Japan-Korea Treaty of 1910 was abolished, certain products were freely imported or allowed to be consumed by Koreans without revealing their origin, mainly comic books and animations for children. In fact, almost all animations shown on TV in the 1960s, 1970s, 1980s and 1990s were Japanese. When broadcast on television, only the full credits for the dubbing were present, and all Japanese cultural references were removed, like Japanese words originally on screen left blank. Episodes completely with overt references to Japan and Japanese culture were "banned" from broadcast. Japanese comic books (manga) were copied by Korean cartoonists and were widely available from the 1960s up to the 1990s, either as direct copies or imitations of Japanese originals. The origins of the mangas were kept secret and most consumers did not realize they were Japanese. Before 1998, more than 75% of all comic books sold in Korea were "Japanese". Video game consoles were also affected. For example, the Nintendo Entertainment System (not the Japanese Family Computer) was released as the Hyundai Comboy (현대 컴보이) by Hyundai Electronics. Feeds of television programs from Japan were also somehow available in the Busan region of South Korea, likely due to the advanced technology and diversity of Japanese television.
Revisions to the laws (1998-2003)
First stage opening (1998-1999)
In October 1998, President Kim Dae-jung gradually lifted the ban on Japanese cultual products, claiming that "it will be a stimulus to society and will help to further develop South Korean culture". The revisions of the laws allowed manga and other Japanese publications, including the Pocket Monsters (Pokémon) anime, which premiered in July 1999.
The first stage opening of Japanese media only allowed live action films awarded the grand prize at three major film festivals, as well as video releases for all films which received a theatrical release.
One example was Kagemusha, which was released in Japan on April 26, 1980, and in South Korea on December 12, 1998.
Second stage opening (1999-2000)
In this stage, any Japanese film classified as "All Ages" were allowed for screening, but animated films remained banned until June 2000.
Love Letter was one of the first randomly selected Japanese films suitable for all audiences to legally enter the South Korean market, having been released in theaters on November 20, 1999.
Third stage opening (2000-2003)
Before 2000, animated films could only be released directly to VHS, due to the restrictions laid out to anime since the mid-1960s. It was by late 2000 when films with their original Japanese credits were now allowed to appear in South Korean theaters.
Pocket Monsters: Mewtwo Strikes Back was one example. Because it was an animated film, it didn't legally enter the South Korean market until after June 2000. The film actually came out on December 23, 2000.
Through the end of 2003, all Japanese films also rated 12+ and 15+ were permitted, as well as animated films awarded prizes at select film festivals. This did not apply to films rated 18+, unless they were grand prize winners.
Korean culture today (2004-Present)
As of January 1, 2004, with the fourth and final stage opening, for the first time ever, all censorship has been lifted on Japanese media in South Korea. This included movies of any rating, music (except on terrestrial television), video games, and television programming. Full access to all Japanese animation, including any motion picture, began in January 2006.
As a result of massive changes to the censorship guidelines for Japanese films, My Little Pony: The Movie ended up taking one month longer to get a release in South Korea than all Doraemon and Pokemon movies from 2009 to 2017 (at least 15 from both film franchises combined), as well as at least one live action Japanese film (Narratage). Worse yet for this non-Japanese film, it wasn't even close to being more successful than any Japanese film whatsoever because this movie didn't get a theatrical release in Korea despite being completely unaffected by the country's historic Japanese rule.
There are still a few laws restricting Japanese media in South Korea. It is only illegal to broadcast music and television dramas over terrestrial signals, but anywhere else is permitted.