Takamiya Naho (voiced by Hanazawa Kana) is an ordinary second-year high school girl. Naho, who is gentle and always considerate of others, is very popular with her friends. One day, Naho unexpectedly received a letter. What she couldn't believe was that the signer of the letter was actually herself 10 years later. Although Naho didn't believe this supernatural development, she still read the contents of the letter carefully. The letter said that there would be a new transfer student named Naruse Sho (voiced by Seiichiro Yamashita) in Naho's class, and Naho would like Sho. What shocked Naho even more was that the letter also recorded that Sho would die in a car accident at the age of 17. Although Naho didn't even know the boy named Sho at the moment, what should Naho do if the content of the letter was true?