In the early days of the Showa era in Matsuyama, Ehime Prefecture a newborn baby is abandoned with a doll under the eaves of a merchant house along the pilgrimage route in Shikoku. It seems to be a pilgrim struggling to make a living. This baby girl is named Haruko and brought by Tomita Shizuko and Katsuji as the younger sister of their son Ryosuke who is three years apart. When the war begins, 16-year old Ryosuke qualifies for the naval academy and crosses the Seto Inland Sea. After some consideration, Shizuko tells Haruko the truth that they are not real siblings for the first time. Haruko who has had a secret crush on her brother ever since he said that he would protect her, is innocently overjoyed and heads to Hiroshima to convey this to him. The next day, an atomic bomb explodes in the sky… After Japan’s defeat in the war, Ryosuke is forced to return home. He cannot believe that Haruko is dead and feels tormented by a sense of loss. As he wastes his life away, he meets Amamoto Ichiko who is a member of a travelling troupe and is attracted to her. However, it is his younger sister Haruko that he sees. Ryosuke eventually comes to a decision.
(Source: jdramas.wordpress.com)