One day, Takamiya Naho receives a letter written to herself from ten years in the future. As Naho reads on, the letter recites the exact events of the day, including the transfer of a new student into her class named Naruse Kakeru. The Naho from ten years later repeatedly states that she has many regrets, and she wants to fix these by making sure the Naho from the past can make the right decisions—especially regarding Kakeru. What’s more shocking is that she discovers that ten years later, Kakeru will no longer be with them. Future Naho asks her to watch over him closely.On the day that Naho begins 11th grade, she recieves a letter from herself ten years in the future. At first, she writes it off as a prank, but as the letter’s predictions come true one by one Naho realizes that the letter might be the real deal. Her future self tells Naho that a new transfer student, a boy named Kakeru, will soon join her class. The letter begs Naho to watch over him, saying that only Naho can save Kakeru from a terrible future. Who is this mystery boy, and can Naho save him from his destiny? The heart-wrenching sci-fi romance that has over million copies in print in Japan!