It’s the spring of Naho’s second year in high school, and Naho receives a letter from herself, 10 years in the future. The letter accurately depicts what’s about to happen, including details on a transfer student from Tokyo, Kakeru Naruse, who ends up sitting beside her in class. On top of that, the letter also begs Naho not to invite Kakeru out with her group of friends on that day alone, but why?

Up until now, Naho had been doing everything the letter from the future had told her to do, but is the letter always right? The letter from the future asks Naho to make sure Kakeru doesn't run the relay race at the athletic festival, but what does Naho decide to do?