At the start of summer vacation Mirai, a middle school freshman girl, travels to Tokyo's artificial Odaiba Island to visit a robot exhibition with her brother Yuuki. A magnitude 8.0 earthquake emanates from an ocean trench, the famed Tokyo Tower and Rainbow Bridge crumble and fall, and the landscape of Tokyo changes in an instant. Luckily the two children meet Mari, a motorcycle delivery woman, on Odaiba, who helps Mirai and Yuuki head back to their Setagaya home in western Tokyo.

[Source: Anime News Network]