Naho is so concerned about Kakeru’s date with Ueda-senpai over the holidays, she can’t help but seem preoccupied and unable to focus on her friends’ conversations. Ever since Kakeru started dating Ueda-senpai, Naho has found it difficult to have a proper conversation with him. Naho regrets not directly telling Kakeru how she really felt the day Ueda-senpai asked him out, but what will she do now?

It's the last day of the school festival. Naho and Kakeru have promised to watch the fireworks together. However, just before they start, Ueda-sama gets in Naho's way. Will Naho get to experience watching the fireworks with Kakeru like her future self did?

The letter from the future details the regret felt by everyone for being unable to celebrate Kakeru's birthday. As such, high school Naho and the gang pester Kakeru about what he wants until the big day. On the other hand, 26 year-old Naho and the gang gather at the late Kakeru's grandmother's house to celebrate his birthday, like they had promised in the past.

Naho feels relieved now that she has the support of all her friends. On top of that, Kakeru and Naho begin to get even closer. Finally, the day of the athletic festival comes. What do Naho and the gang do to insure Kakeru can enjoy the festival from the bottom of his heart?

It's the athletic festival. Kakeru hurt his ankle during the pole-toppling game, and hid that fact from everyone else. Kakeru tries to keep his suffering to himself, when Suwa and the gang call out to him. Met with everybody's kindness, Kakeru begins to tell them what he's been keeping pent up inside. And then, the class relay begins.

Kakeru moves to Matsumoto with his mother mother after she decides to move there for her own reasons. When she passes away on the first day of school after Kakeru transfers, Kakeru blames himself and thus refuses Suwa's invitation to join the Soccer club. Kakeru sees some old classmates from Tokyo, but none of them understand what Kakeru is going through. In the end, Kakeru becomes so distressed that he feels that he has no way out.

Naho can't give her Valentine's Day chocolate to Kakeru. Ever since what happened on New Year's Eve, Kakeru keeps putting distance between Naho and himself. But, through all the hardships, Naho refuses to give up and fully intends to tell Kakeru how she feels. And so, the time comes for everyone to face the fateful day outlined in the letters from the past, "Kakeru's Final Day."