Based on Sakyo Komatsu's 1973 bestseller sci-fi novel Japan Sinks. The story is set right after the 2020 Tokyo Summer Olympics, and follows the fate of the four members of the Muto family, including the protagonist girl Ayumu and her younger brother Gou.
Because it is populated by TOP 10 ranking since 2020, it is still a work in progress. Multiple links in the same country lead to different streaming versions.