Two years ago, Junichi asked his childhood friend Rihoko, to come and help him select a present for his date on Christmas Eve. Rihoko, who had an unrequited love for Junichi, was sad to find out later that he was stood up. In the present, Rihoko takes a shortcut to school through a hole in a fence, but gets stuck until Junichi helps pulls her out. Realizing she is gaining weight, she seriously swears to her friend Kanae that she'll go on a diet immediately, and gives her cupcakes to Junichi. Kanae seizes this chance to invite him and Masayoshi to go ice skating with them in the weekend. However, upon visiting her seniors at the Tea Club, Rihoko unwittingly breaks her diet there eating snacks until Manaka and Ruriko remind her. Eventually Junichi walks a sulking Rihoko home and even pass by and play on the slide where they and Miya played on as kids. After checking the scales that night, she swears to go on a diet.

Rihoko tries her best ice skating with Junichi, unaware that it’s a part of Kanae’s plan to get them together. At school, while Rihoko sends in the Tea Club’s application for the Founder’s Festival, Junichi meets Manaka and Ruriko and helps them carry a kotatsu to their club room. Manaka and Ruriko convince Junichi to help the Tea Club during the Festival and hopes he joins their club as well. On the night of the festival, the Tea Club, wearing Kimonos, serve tea and sake for their guests while Junichi and Rihoko head out and distribute recruitment fliers. After the festival, Rihoko and Junichi go home together where she gives Junichi his Christmas present. Since he has nothing to give her, Junichi grants Rihoko a chance to ask him any favors.

With the festival over and the school cleaning up, the Tea Club invites Junichi for tea as thanks for helping them where the latter gets interested and learns how to make tea from them. While eating at the restaurant where Kaoru works at, Rihoko asks Junichi to accompany her to go the local shrine on New Year’s Eve. But when Junichi and Rihoko are about to go with Miya, the latter two falls asleep, making them go the shrine in the morning instead. As they pray and check their fortunes, Rihoko writes down on an ema Junichi gave her earlier and wishes for a successful diet, new members joining the Tea club, and, as a quick addition, tell her feelings to Junichi someday.

As the new term is about to start and graduation coming soon, Rihoko works hard to recruit people to join the Tea Club before Manaka and Ruriko graduate. During Valentine’s Day, Rihoko gives Junichi a box of chocolate cream puffs. As he eats them, she asks him if there is any girl he would like to receive chocolates from which he in turn asks if there’s anyone she wants to give them. On the day of their graduation, just as Rihoko reports to her seniors that she failed to get any new members, Junichi later arrives and reveals as a graduation present for them, he is joining the Tea Club. In the epilogue set at the new school term, Junichi and Rihoko prepares a Freshmen Tea ceremony for potential members, with Kanae, Manaka and Ruriko also being invited. While enjoying the success of the Tea Ceremony, Rihoko hopes to one day tell Junichi how she feels about him.

Still in pain after being stood up a year ago, Junichi decides to skip the Founder’s festival when Masayoshi catches up with him and invites him at his house. A year later, Junichi decides to change himself, and he starts by volunteering as Tsukasa's assistant for the Founder's Festival committee, to everyone's surprise. Junichi is amazed with Tsukasa's work ethic and the work she does. While being locked in the storage room, Junichi tries to get to know more of Tsukasa until Miya and Sae arrives. On their way home, Junichi meets her older sister Yukari on the way but Tsukasa shows displeasure and hurriedly excuses herself and drags her sister home. The next day, despite Tsukasa being busy substituting swimming classes for Kaoru and Keiko, she is able to help Junichi deal with problems concerning the festival. Later that afternoon, Junichi finds a notebook on the classroom floor. As he tries to find the owner's name inside it, Tsukasa, still in her swimsuit, suddenly arrives.

Tsukasa drags Junichi to the local shrine and learns he never really read her notebook. However, she blackmails him to keep her other personality a secret. But when he tries to talk about it with Masayoshi, Tsukasa catches him red-handed and forces him to work very hard in helping with the festival. While working late one night, Junichi finds Tsukasa painting one of the festival’s attractions. He learns that she works very hard and takes important positions in school to maintain her image and reputation as a school leader. The next day, Kaoru tells Junichi that Tsukasa passed out from overworking so he visits her at her home to give her some bananas and energy drinks. During the visit, Junichi notices how serious Tsukasa is compared to her carefree older sister. The next day, Tsukasa is back to normal and helps Hibiki with entering the Miss Santa contest and what she can wear.

With the festival behind schedule and Tsukasa's health worrying her, Miss Takahashi suggests they cancel some events, but Tsukasa assures her the festival will be ready unchanged. Knowing that the festival committee is short of manpower, Junichi manages to convince Tsukasa to get their class to help. However, a trio of girls complain and accuses Junichi and Tsukasa's flirting with each other as the root of the festival’s problems. When she fails to end the argument nicely, Tsukasa switches to her real personality and cites the trio’s hypocrisy, silencing and shocking everyone. Later, Tsukasa brings Junichi to the shrine again where she burns her notebook, makes him promise to be hers and seals the deal with a kiss. The next day at PE class, Tsukasa is ganged up by the trio again in dodgeball but the rest of class sides with her, forcing the trio to give up. However at noon, only Masayoshi, Keiko, and Kaoru remains to help Junichi and Tsukasa.

Despite the cheerful atmosphere going into finishing work for the Founder’s Festival in time, Junichi is sad about Tsukasa, and plans to ditch the festival again. But when Masayoshi reveals to Junichi about a girl he never got to confess at grade school, he tells Junichi not to make the same mistake as he did, inspiring him and regaining his composure. At the Festival's after-party, Junichi asks Tsukasa for some time alone, and confesses to her. But when he says that he loves her no matter what her personality is, she, confused and angry, beats him up, telling him she erased the old her for him before crying into his arms when Junichi expresses how glad he is to know the Tsukasa he loves still exists. Miss Takahashi catches the two but decides to leave them alone. Tsukasa later tells Junichi that she began organizing the Founder's Festival as a childhood dream to become Santa Claus herself to make people happy but now realizes she's doing it for her own fulfillment.

A shy girl named Risa Kamizaki confesses to Junichi, which the latter accepts and agrees to become her boyfriend, but she wants to keep their relationship a secret. Junichi wants to go the Founder's Festival with Risa and wishes to introduce her to his friends, but, after some thinking, she refuses. Unknown to him, Risa's reasons for not wanting to come is because at the time when he was getting close with Haruka, Kaoru, Sae, Ai, Rihoko and Tsukasa, she was stalking him and prevented the girls from falling in love with him by showing them a doctored photo that Junichi already has a girlfriend. Later, while visiting the park where he was stood up two years ago, Junichi meets Makihara, the girl who stood him up. To his surprise, Makihara never stood him up because a classmate of hers told her that he was waiting for her at the cinema.