Plot

High school student Naho Takamiya receives a letter from her future self that warns her to avoid mistakes she will make involving a new transfer student, Kakeru Naruse, a troubled boy whom she meets and begins to fall in love with.

Naho Takamiya's first day of her sophomore year of high school is off to an uneasy start. After waking up late, she receives a strange letter addressed to her. However, the letter is from herself-10 years in the future. At first, Naho is skeptical of the note; yet, after witnessing several events described to take place, she realizes the letter really is from her 26-year-old self. The note details that Naho's future life is filled with regrets, and she hopes that her younger self can correct the mistakes that were made in the past. The letter also warns her to keep a close eye on the new transfer student, Kakeru Naruse. Naho must be especially careful in making decisions involving him, as Kakeru is not around in the future. With the letter as her guide, Naho now has the power to protect Kakeru before she comes to regret it once more.—MAL Rewrite

During the spring of her second year of high school, Naho receives a letter. Its sender is herself from ten years in the future. Naho thinks it's a prank at first, but when the things written in the letter start to come true one by one, she realizes that the letter is telling her events that will happen in her future. It tells her that she'll fall in love with Kakeru, a new student who transfers to her school, and that he'll die in the winter of his 17th year. After learning the regrets and wishes of the 26-year-old Naho following Kakeru's death, what can the 16-year-old Naho do differently?—Crunchyroll