A group of Yokohama students fight to save their school's clubhouse from the wrecking ball during preparations for the 1964 Tokyo Olympic Games. While working there, Umi and Shun gradually attract each other, but face a sudden trial. Even so, they keep going without fleeing the difficulties of reality>
Umi has a bob with lightly swept bangs with braids and hazel eyes. She is seen in her school uniform including a blue skirt, white shirt and blue line with a red ribbons tied around her neck in a bow, which resembles her grade. Umi's causal wear consists of a light pink top with a hot pink skirt and sweater. Umi is a 16-year-old girl living in Coquelicot Manor, in Yokohama, Japan. She also known as "the girl who raises flags," because she raises the same pair of signal flags every morning and takes them down every night. When Umi was just a child, her father, a captain, taught her how to raise signal flags and explained that the flags meant "safe voyages." After learning how to raise signal flags, she raised the flags every time her father left port and only took them down when her dad's ship moored at the harbor. However, her dad was killed in the Korean War, when his supply ship struck a mine. Although, she continued to raise the flags hoping her message would reach him. Also, she pays her respects to her father with fresh flowers and a glass of water every morning.
Shun Kazama is a seventeen-year-old boy. He has dark brown hair and black eyes. One day, a poem about the flags being raised is published in the school newspaper. Shun Kazama, the poem's author, witnesses the flags from the sea as he rides his father's tugboat to school. At first, Umi gets the wrong impression of Shun as he does a rash stunt on behalf of the "Latin Quarter", an old building housing their high school's clubs that's being threatened with demolition. Upon her sister's request, Umi accompanies her to obtain Shun's autograph at the Latin Quarter. She learns that Shun publishes the school newspaper, along with Shirō Mizunuma, the student government president. Umi convinces Shirō and Shun to renovate the Latin Quarter, and all the students contribute, both boys and girls. Umi and Shun start having feelings for each other.