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?

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.

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?

Kakeru gives Naho a hairpin. And on the weekend, Kakeru invites Naho to study with him for the upcoming exams. As the pair begin to grow closer together, Naho gets up the courage to invite Kakeru to see the fireworks together with her at the end of the school festival.

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?

In the letter, it says Kakeru won’t join the soccer club, but in reality, he does. This difference between the letter and reality fills Naho with hope, as she believes it may mean that the future is starting to change for the better. But just as she begins to think that, she has to deal with the letter detailing how Kakeru and Ueda-senpai begin to date...

Kakeru enters the soccer club as a provisional member, just as the letter says. When the topic of lunches comes up after practice, Kakeru jokingly asks Naho to make lunch for him as well. Naho finds herself bewildered by his words, but feels pushed to act by the letter from herself 10 years in the future, which tells Naho that she wishes she had made lunch for Kakeru.

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."

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 got into a fight with Kakeru on New Year's Eve, and never managed to apologize to him before he passed away. At least, that's what the letter from the future says. However, Naho now believes that she's capable of dealing with whatever may come up, and faces New Year's Eve head-on.

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.

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?

After causing a catastrophe in the New Year’s Tournament, Jyugo and Musashi are sent to the underground cell. To solve the mysteries of their powers, Kenshirou suggests allowing the two to speak to one another. Unable to move freely, Musashi gives Jyugo information on the man with the scar.Listening to their exchange, Hajime tells Jyugo he’s empty. Hajime’s words confuses Jyugo.

The shackles have been triggered and Jyugo’s hands transformed into blades. He attacks Musashi and splits the arena in half. The arena becomes chaotic and Momoko orders Hajime, Kenshirou, Samon, and Kiji to apprehend Musashi and Jyugo. Musashi retaliates against the guards while Hajime stands in Jyugo’s way.

Tsukumo heads to the visiting room during the break from the New Year’s Tournament. His manager, Hattori, has come to visit. People think the famous action star is missing and has no idea he’s in prison. Hattori persuades the talented Tsukumo to come back into stardom. However, already uninterested in being a star, Tsukumo talks about his upbringing.

Cell 13 has advanced their way to the final event of the New Year’s Tournament. Jyugo and Hajime are battling against the Building 4 supervisor, Kenshirou Yozakura, and an inmate named Musashi. Jyugo is surprised to see Musashi again. Musashi, in search for the “man with the scar on his neck,” attacks Jyugo mercilessly. Soon as Jyugo hears about the man with the scar on his neck, something odd starts happening to his body.

Jyugo and the gang are advancing through the New Year’s Tournament without a hitch. In the Hyakunin Isshu event, Uno wins against the Building 3 inmates, Trois and Honey. The 4th event is a physical match revolved around a spinning top, but Niko unintentionally enters the match. The opponent is Upa, a kung-fu expert from Building 5. Does Niko, the otaku, have any chance of winning?!

Nanba's New Year Joint Cooperation Tournament, aka New Year’s Tournament, begins by gathering the entire inmates. Jyugo and the others are enthused once they hear the winner gets to choose whatever he wants. However, all the matches are odd events relating to New Year’s. Can Building 13 win against the other inmates led by peculiar guards?

Jyugo and the gang are killing time teasing the new guard, Seitarou. One day, a new inmate is sent to Cell 13. Inmate Number 99, Tsukumo. He looks and acts like a ninja! Uno, Niko, and Rock are excited to see the real thing. But as a Japanese, Jyugo does not believe him. To convince Jyugo that he’s a true ninja, Tsukumo challenges Jyugo to see who can escape from prison...

Jyugo heads toward the cell Hajime is trapped in on his own. In the underground level 2, Uno, Trois, and Honey are looking for a certain guard relying on the smell. Enki finds out Jyugo and the others have escaped. Bruised all over, Jyugo finally reaches to Hajime’s cell on level 5. However, Hajime says something very heartless to Jyugo.