Three moments in Takaki's life: his relationship with Akari and their forced separation; his friendship with Kanae, who is secretly in love with him; the demands and disappointments of adulthood, an unhappy life in a cold city.

In a post-war alternative timeline, Japan is divided into the North, controlled by the Union, and the South, controlled by the United States. A mysterious high tower rises within the borders of the Union. Three high school students promise to cross the border with a self-built airplane and unravel the secret of the tower.

It was 1935, people were afraid of the outbreak of the war. The story began in a beautiful island surrounded by the Arctic Ocean of Europe. There was a boarding school, Rosenstol School, in which young elite students gathered. The story describes the youth of five elite students who were elected to be the top of the school to realize their dreams and ideals.