While the Second World War rages, the teenage Mahito, haunted by his mother's tragic death, is relocated from Tokyo to the serene rural home of his new stepmother Natsuko, a woman who bears a striking resemblance to the boy's mother. As he tries to adjust, this strange new world grows even stranger following the appearance of a persistent gray heron, who perplexes and bedevils Mahito, dubbing him the "long-awaited one."
Yokohama, 1963. Japan is picking itself up from the devastation of World War II and preparing to host the 1964 Olympics—and the mood is one of both optimism and conflict as the young generation struggles to throw off the shackles of a troubled past. Against this backdrop of hope and change, a friendship begins to blossom between high school students Umi and Shun—but a buried secret from their past emerges to cast a shadow on the future and pull them apart.
In the aftermath of the most devastating conflict mankind had ever experienced, the tiny island of Shikotan became part of the Sakhalin Oblast... and on the unhealed border in this remote corner of the world, friendship among children from two different countries timidly blossomed, striving to overcome language barriers and the waves of history. Inspired by true events.
Kaji, sent to the Japanese army labeled Red, witnesses cruelties in the army and revolts against the abusive treatment against a fellow recruit. He also sees his friend Shinjô defecting to the Russian border, and he ends in the front to fight a lost battle against the Russian tanks division.