The continuing story of Japan's submersion into the depths. As the Japanese population is spread through out the world, trouble arises from those nations. America, Australia and European countries continue to persecute the 30 million Japanese people that their populace and economies have to support.

After the immense success of Submersion of Japan in 1973 and its subsequent TV series from Toho and TBS in 1974, it should come as no surprise that Toho had contemplated a big screen sequel to the concept. This was first conceived back in 1974, when the TV show was in production and literally titled "Continuation: Submersion of Japan". The film project would have reunited most of the principal staff from the first film, including director Shiro Moritani, special effects director Teruyoshi Nakano and producers Tomoyuki Tanaka and Osamu Tanaka. The company was confident enough in the production that advanced posters started to appear in theaters in Spring of 1974. While not much is known at this stage, the concept was going to focus on the escaping Japanese population.

By 1976, the concept was still kicking and planned for a release that year. The idea was fleshed out a little more, as it was to be centered on the persecution of the millions of Japanese in America, Australia and Europe who had to escape after Japan's destruction.

Lamenting in preproduction, the project was still showing up as a planned release for 1978 when Toho issued their annual lineups. Sadly, this would be the final time Continuation: Submersion of Japan would get a proposed release before the concept was permanently shelved.