Five years ago Shinpei (Mizobata Junpei) was a flag carrier for the Ichimujin team at the Yosakoi festival in Kochi, Japan. Shinpei now lives in Tokyo and aims to become a cameraman, while working as an assistant cameraman to Takaki Shiro (Fujiwara Tatsuya). Although he is busy with his work he is also losing confidence in himself. Then one day, he hears that his mother has been hospitalized and returns to Kochi for the first time in five years.
While at the hospital Shinpei meets young Nogami Sakura (Omori Ayane), who is the younger sister of his ex-girlfriend from high school Nogami Kaori (Kinami Haruka). Back then, Shinpei made a promise to Sakura that they would one day dance together in the Yosakoi festival. Sakura now lives with a terminal disease which no one has lived with for more than 5 years. This might be her last summer.
Sakura begs her father and sister Kaori to dance at the Yosakoi festival no matter what happens. Sakura still remembers the promise that Shinpei made to her and that promise also gives her the drive to live longer. Kaori, knowing how much that promise means to Sakura, tells Shinpei of her wishes. He becomes embarrassed at first, but remembers fondly of their time together. Shinpei then decides to dance once more at the upcoming Yosakoi festival & thus gathers the ex-members of his dance team to practice.
Right when the festival is around the corner, Shinpei's senior assistant Ishiguro Tomoya (Daigo) from Tokyo informs him that he won a prestigious award. The award is a virtual gateway to becoming a cameraman. Tomoya applied on behalf of Shinpei without Shinpei's knowledge. Shinpei also learns that the award ceremony takes place the same day as the Yosakoi festival. Furthermore, Shinpei can't win the award if he is absent from the ceremony. Shinpei must now pick between his dream and his promise.