The movie follows the story of Naho Takamiya (played by Fukushi Sayo), a high school student who receives a mysterious letter from her future self. The letter warns Naho about a series of events that will unfold, including the transfer of a new student named Kaji (played by Kento Yamazaki) to her school. The letter also urges Naho to be kind to Kaji and to prevent a tragic event from occurring.
The soundtrack was a major highlight and received critical acclaim.