In 2004, Yui Yoneda (Kanna Hashimoto), who lives with her father Masato (Yukiya Kitamura), a farmer in Itoshima, Fukuoka Prefecture, her mother Aiko (Kumiko Aso), her grandfather Eikichi (Ken Matsudaira), and her grandmother Kayo (Yoshiko Miyazaki), enters high school. She talks about club activities with her childhood friend Yota (Araki Sugou) and her classmate Emi (Shuri Nakamura). Yota decides to join the baseball club, and Emi the calligraphy club, but Yui can’t think of any particular club she wants to join. One day after school, Yui encounters an unexpected situation at the fishing port she often visits to see the sea.

After school, the heroine Yui (Kanna Hashimoto) is suddenly surrounded by a group of gyaru girls, and just when it seems like she might get beaten up, they invite her to join a gyaru group called the Hakata Gyaru Alliance (Hagyalen). It turns out that Yui's older sister Ayumi (Riisa Naka) was the first leader of Hagyalen and was a charismatic figure among the gyaru. When Yui returns home and talks about the gyaru group during dinner with her family, an argument unexpectedly breaks out between her father Masato (Yukiya Kitamura) and her grandfather Eikichi (Ken Matsudaira).

Yui (Kanna Hashimoto), who joined the calligraphy club, starts to feel drawn to her senior Kazami (Matsumoto Leo) and feels like she's enjoying her youth. However, even when her classmate and fellow calligraphy club member Emi (Shuri Nakamura) hands her the official club application form, Yui hesitates to join. Yet, when she hears that her senior will be attending a calligraphy exhibition held in Tenjin, Fukuoka, she immediately decides to go. At the Yoneda household, Yui’s mother Aiko (Kumiko Aso) listens to her story and worries about Yui's hesitation to join the calligraphy club.

Yui (Kanna Hashimoto) runs into the gyaru girls near a game center in Tenjin, where they persistently push her to join the Hakata Gyaru Alliance, leaving her in a tough spot. Just then, the police arrive. It seems that a salaryman who saw Yui and the gyaru girls mistook the situation for extortion. The gyaru girls protest, insisting they haven't done anything wrong, but the man judges them by their appearance and calls them scum of society.

On Sunday, Yui (Kanna Hashimoto) arrives at Fukuhaku Bridge, the meeting spot, to go to the exhibition with her admired senior from the calligraphy club, Kazami (Matsumoto Leo). Yui's heart flutters at the sight of Kazami in his casual clothes. As they head towards the exhibition together, Yui spots Suzurin (Natsumi Okamoto), a gyaru from the Hagyalen group, handing out tissues. To avoid being seen, Yui walks while hiding behind Kazami. In the midst of this, Suzurin suddenly starts to wobble and collapses to the ground.

Unable to ignore someone in need, Yui (Kanna Hashimoto) helps the gyaru, driven by the kindhearted nature of the Yoneda family. This leads to Yui secretly starting to interact with the gyaru from the Hakata Gyaru Alliance (Hagyalen), which her sister Ayumi (Riisa Naka) had formed long ago, without her family knowing. On weekdays, she participates in the calligraphy club with her admired senior Kazami (Matsumoto Leo), while on weekends, she spends time with the gyaru, living a double life. Meanwhile, Yui's father Masato (Yukiya Kitamura) reflects on the words from Eikichi (Ken Matsudaira) regarding his approach to farming.