With Sakuta's help, Kaede is able to go to school at night. She is now enthusiastic about heading to school during the day. However, on the following day, the original Kaede's memory suddenly returns, eradicating all memories of the Kaede that had spent the last two years together with Sakuta. A certain person appears before Sakuta, who is overwhelmed with grief because Kaede was no longer around.

After her boyfriend Takumi Fukuyama was unable to remember who she is, Nene completely forgets her own identity, and believes that she is Touko Kirishima. The only person who can correct this Puberty Syndrome is Takumi, and Sakuta believes doing so will help him protect Mai. He and Ikumi Akagi rush off to Hokkaido, where Takumi’s hometown is. As Takumi welcomes them at the airport, Sakuta shows the trophy that Nene won at a beauty contest...

Even after leaving Fujisawa for Ogaki, not one person remembered anything about Mai Sakurajima. Sakuta and Mai return to school together, but even there they hear from Sakuta's friend Rio Futaba that nobody at school outside of her has any recollection about Mai. At the same time, Sakuta hears of a theory that losing memories concerning Mai is based on a certain action taken, and struggles so that he doesn't lose his memories of her. And seeing Sakuta act as such, Mai makes a certain decision of her own as well...

It is now the last day of the first term, the promised day when pretending to be dating Tomoe ends. It seems as though everything has finally been resolved, but…

With Nodoka's Puberty Syndrome resolved, Sakuta's expectations to spend sweeter times with Mai is growing. But then, a scandal is reported by the media about Mai Sakurajima having a new boyfriend. In the press conference for a movie she had a role in, Mai gives a sincere explanation. Seeing that, Kaede decides to set goals for the rest of the year, wanting to do her best for Sakuta's sake as well. One of the goals she writes down is to go back to school...

Sakuta unveils to Mai and Nodoka the details of his family's past, and the trauma that Kaede underwent. Meanwhile, Kaede continues her re-integration into society, but as more hurdles appear, Sakuta worries for his sister's well-being.

Sakuta sees a familiar Miniskirt Santa on a beauty pageant website that his friend Takumi Fukuyama was looking at. However, he notices that her name isn’t listed as Touko Kirishima, but rather as Nene Iwamizawa. As he continues his search for Touko Kirishima, he receives an offer of help from Sara, which he accepts. One of the symptoms of her Puberty Syndrome includes knowing what a person she has collided with is thinking, and that’s how she figured out that Sakuta was looking for Touko Kirishima. Sara suggests reading the Miniskirt Santa’s mind at the venue where she’ll perform her new song live on Christmas Eve.

Upon inducing a case of "Puberty Syndrome" where two copies of herself exists, Rio ends up staying at Sakuta's house for the time being. Meanwhile, "the other Rio" has been busy posting various unexpected photos on social media. After being informed about these activities by his classmate, Saki Kamisato, Sakuta decides to have a chat with "the other Rio." As he learns more about each of the Rio-s in hopes of discovering the reason for "the other Rio’s" actions and possibly a cure for her "Puberty Syndrome," Sakuta begins to realize the troubles each of them carries...

Uzuki begins blending into her friend group’s dynamic as her popularity grows.

A Miniskirt Santa suddenly appears before Sakuta. She says her name is “Touko Kirishima” and claims to have been handing out Puberty Syndrome to people as gifts. Sakuta sees her eyes lock on Ikumi Akagi, a former middle school classmate who is attending the same university as Sakuta, studying in the nursing program. Curious about Ikumi, Sakuta goes on a group date with female nursing program students that his friend invited him to. There, they discuss a rumor about people’s dreams coming true after they post about them on social media with the hashtag #DREAMING...

It’s the day of Sweet Bullet’s performance in an ensemble concert at a venue in Odaiba.

A pumpkin lantern made of glass comes crashing down in a plaza in front of Sakuragicho Station, just as a social media post with the hashtag #DREAMING had predicted. However, Ikumi rushes in to protect a girl who was running directly underneath it as it falls, preventing any injuries. She believes the rumor about the #DREAMING posts and has been going around saving people. Ikumi visits Sakuta at the university and passes him an invitation to their middle school reunion. Sakuta warns her about helping people too much, but she ignores this advice...

Sakuta has started attending university and meets a girl during a group outing.

A poltergeist-like phenomenon attacks Ikumi. Sakuta is worried the attack was caused by Puberty Syndrome, but Ikumi claims that the only way to fix this problem is by forgetting about Sakuta’s existence. Hearing this, Sakuta is stunned and confused. Without giving him the time to compose his thoughts, Ikumi proposes that they have a contest, competing to see if Sakuta will remember “that day” first, or if Ikumi will forget about Sakuta first.

Sakuta has a dream that Mai reveals herself as the true identity of Touko Kirishima at a music festival held on April 1st. At the same time, several major social media platforms were being flooded with posts containing the hashtag #DREAMING, leading to platform crashes and access errors. As the hashtag #DREAMING causes chaos among the public, Tomoe Koga tells Sakuta that she had a dream that Mai got into an accident, rendering her unconscious during an event where she was collaborating with the police for a public safety awareness.

Sakuta had been unable to see Mai, who was not only busy with work but had an order from her agency forbidding her from going on dates. The second term finally begins, and Sakuta is eagerly looking forward to seeing Mai again at school. But upon seeing Mai in front of his house, she greets him with a shocking, "Who the heck are you?" Upon confirming what the circumstances are, it comes into light that Mai and her little sister Nodoka Toyohama have swapped bodies. Until this new Adolescence Syndrome is resolved, Mai will be living as Nodoka, and Nodoka will be living as Mai...