|Season 1, Episode 1|
|Air date||July 3, 2016|
|Written by||Takano Ichigo|
|Directed by||Hiroshi Hamasaki|
A short intro where 26 year old Naho Takamiya and her friends intend to send letters to their 16 year old counterparts. Naho starts her story on how she regret every moment in her life and decides to tell her 16 year old counterpart on dealing her misfortunes. 10 years earlier, Naho woke up late and receives a letter, which came from her adult self. She read the first page of the letter at school and it seems accurate that she is indeed late. It also tells that a transfer student will sit next to her, and it happened. Kakeru Naruse introduces himself and sit next to Naho. As the class dismisses earlier, Naho and her friends decide to stroll along, get acquainted and make friends to Kakeru. At night, Naho read the letter again and notices the similarity in her writing and contents of her diary and the letter. The following days Naho notices Kakeru's absence. At the PE class, she read the letter that she will not join the softball game and this will cause her to regret it. A returning Kakeru chats with Naho regarding joining a sports club and her injured foot due to the size of her shoe. At the softball game, Naho's teammates invite her to play and becomes hesitant first. But due to the letter and a little inspiration from Kakeru, she stands up and play as the batter in their softball game. Naho hits the ball and it goes homerun, winning the game and their class also become champions because Suwa also wins the football game. Naho now completely believes that the contents of the letter are all real and happened, and she read the next pages it reveals that Kakeru will die. The letter asks a favor to Naho that she must look closely on Kakeru.