Arata Natsume works at a child guidance center, is in his thirties and single with no plans for marriage. But one day, he receives a request from the child he was in charge of, Takuto, to "meet the criminal ...

In the Spring she was 16, Takamiya Naho receives a strange, but detailed letter from herself, ten years in the future. At first she thinks the letter is a prank, but then the things written in the letter act...