Due to their mother's frequent absence, 11-year-old elementary school student Minato Myoujin and his younger sister, Nagisa, are often left alone in their apartment. The only company that keeps the young siblings optimistic is their neighbor, Futaba Tachibana, and the local shrine's puppy, Zarame. Even with their mother's sporadic presence in their lives, Minato knows that she always eventually comes back home.

After an unusually long two-week absence, Minato's mother returns just in time for Nagisa's birthday. To celebrate the occasion, the three go to the amusement park. However, the siblings' mother leaves them in the Ferris wheel, walking off into the rainy night just before thunder strikes two of the ride's cars. When he regains consciousness, Minato realizes that he has switched bodies with someone—a man wanted by the police for murder! Now on the run, Minato must find a way to return to his body in order to protect his sister.