The Mutou family lives a quiet life: Kouichirou works on a construction site, and his wife Mari has just returned from a trip abroad. Their daughter Ayumu has just finished track practice, while their son Gou is at home playing video games. However, their lives are turned upside down when a devastating earthquake smashes the whole Japanese archipelago, obliterating the country's face in an instant. The Mutou family must join together to escape the disaster as civilization crumbles around them and their nation sinks into the sea. They battle not just to stay alive in the near-apocalyptic situation, but also to learn the challenge of coping with loss.