The Mutou family enjoys a tranquil existence until a devastating earthquake ravages Japan, plunging the nation into chaos. Faced with the collapse of society and the gradual submersion of their homeland, Kouichirou, Mari, Ayumu, and Gou must unite to navigate the post-apocalyptic landscape. Amidst the ruins, they grapple with the harsh realities of survival and the profound challenges of grief and loss.