It struck without warning one fateful day in Tokyo – a massive 8.0 earthquake rocked the city and caused massive devastation and death in its wake. Having taken her little brother to an exhibit that day, young Mirai and he find themselves alone and with no one to turn to – until a kind delivery woman named Mari promises to help them get back to their family. Now, the three travel the ruined cityscape and brave immense danger as they try their best to make their way home.