Hiroto Suwa, 26, his wife, Naho, and their former high school classmates Takako Chino, Azusa Murasaka, and Saku Hagita visit Mt. Koubou to see the cherry blossoms. They talk about Kakeru Naruse, a buddy who died ten years ago, while they watch the sun set. They decide to visit Kakeru's former house, where they hear the truth of his death from his grandma. Suwa and his buddies, filled with remorse, resolve to send letters to their 16-year-old selves in order to put their hearts at ease. Suwa, 16, gets the opportunity to rewrite his destiny with the knowledge provided in the letter from his future self. What decisions will he make? What is going to happen in this new future?