Once a serene and ordered daily routine for the Mutou family, with Kouichirou focused on construction, Mari enjoying her travels overseas, Ayumu finishing up her daily track practice, and Gou lost in his video games, was suddenly shattered by a catastrophic earthquake that wiped out the entire Japanese archipelago in an instant. With Japanese society crumbling and the nation submerging into the ocean abyss, the Mutou family banded together to weather the crisis. Amidst the devastating aftermath, they battled not just for survival, but also to confront the brutal truth of loss and mourning.