At the wedding reception, Eri approaches Ken and asks him whom he gave his second button to. Ken reminisces the time he gave it to a girl who asked for it.
Tada-sensei asks Rei if she ever wanted to receive a second button from anyone. She answers yes but that she didn’t get it. She remembers the time she saw Ken’s uniform was missing its second button.
Eri tells Ken that she had a feeling Rei wanted to have his second button.
Ken wonders if things would have been different if he had given his second button to Rei. Yousei appears before him and allows him to go back in time again.
Ken goes back to the time when he was being prodded to give his second button. He holds on to it but is forced by Mikio and Tsuru to give it away.
Eri and Rei talk about how disappointing and boring their graduation ceremony was. Tsuru gives Eri his second button but she tells him that she doesn’t want it.
Ken is disappointed with the loss of his second button. He tries to hide it from Rei who is asking him to sign her yearbook. Rei tells him that no one would probably ask for his second button so just like in junior high, she’d probably take it from him out of charity.
Ken asks Tsuru and Mikio’s help to get back his button. They devise a plan to get it back.
Meanwhile, Rei explains to Eri why second buttons are that important. Rei tells her it’s because the second button is the closest to the heart. The uniform is something you wear all throughout your high school life so the second button is filled with the person’s feelings. Eri wonders if Rei wants someone’s second button but Rei refuses to tell her who that person is. Rei says the closer you are to that person, the further you are from his second button.
Tada-sensei visits them in school and chats with Eri and Rei about graduation. He tells them about the mark he left in school before he graduated. The three of them go to the chemistry laboratory and find the table in which Tada-sensei carved his name.
Meantime, Tsuru, Mikio and Ken kneel in front of the girl to ask for Ken’s second button back. The girl admits that she only made a bet with her friends and collected as much second buttons as can. She identifies Ken’s button because of the crack and returns it to him but Tsuru gets to it first and throws it over the window. Tsuru is upset because he thinks the girl has made a fool out of them.
Outside, Ken searches desperately for his button. Mikio wonders why Ken is so keen on looking for a button that he already gave to someone else. Ken realizes that the button is meaningless.
Ino-sensei gives the graduation rites for the baseball team.
Before leaving school, Tsuru gives Eri all the buttons of his uniform. As they’re about to go out, Rei notices that Ken’s second button is missing. She pretends that she’s okay with it and that she’s happy Ken found someone else who wants the button.
Mikio’s girlfriend arrives to pick him up and gives him a duplicate key.
At Shogun’s Burger, the girls discuss their disappointment over their graduation ceremony.
They decide to go back to school to do the things they’ve never done before. The five of them sit on the principal’s chair, make coffee in the chemistry lab, play bowling in the school corridor and bury a time capsule under the cherry blossoms. Ken thinks about how happy the five of them are when they’re together.
Mikio, Ken, Eri and Rei go up the rooftop and see Tsuru writing the words “I like Eri” on the baseball field. Ken admires Tsuru’s honesty. As they’re about to leave, Ken stops them and tells them there’s one more thing they haven’t done yet.
They go back to the baseball field and the three guys appear in their baseball uniforms. Tsuru pitches and Ken hits a homerun.
The whole baseball team appears and they give the graduation rights for baseball managers Eri and Rei. They present the two with flowers and fake certificates. The two are touched by the gesture.
Before leaving the field, Rei notices something inside her cylinder. She opens it and sees the second button of Ken’s baseball uniform. Rei is deeply touched.
As they pose for a photo, Ken tries to tell Rei that he likes her but he runs out of time and is transported back to the present.
At the reception, Tada-sensei asks Rei whether she received a second button during graduation. She tells him that she got a weird one.
Ken asks Yousei why it’s so difficult to change things. He answers that a human’s heart is not a simple thing to change.
Next photo on the slideshow was taken during a spring in college. Ken remembers that Rei slapped him because he tried to kiss her as a joke.