In the second year of high school, Nai Sui received a letter from himself 10 years later. She has many regrets in the future, so she sent this letter in order not to let the current Naho have the same regret. The content of the letter is about the transfer student Xiang. From the first day Xiang transferred to Xiang's death, Cai Sui had many opportunities to reverse the future and let Xiang exist in the future 10 years from now. However, the point is not what choice to make, but to really save Xiang&#39