Setsuko loves the sea. She swims its shallows. She dives its depths. But she worries that her friends have chosen to abandon her way of life. Then she meets a whale who also fears he is the last of his kind. In return for giving him hope, he gifts her a song which she uses to remind people of the beauty of the ocean. Setsuko took the song and made it her own. They played together from the first crisp light of morning until the setting of the evening sun. Everyone who heard Setsuko's song was filled with the wonder of the sea. They remembered the beauty and mystery of the ocean. A story of an unlikely friendship, Setsuko and her friend the whale have one thing in common - their love of the sea. Much like the revered ama-san, - women who have been diving off the coast of the Shima peninsula in Japan for over 2,000 years - Setsuko is a strong girl who is on the path to becoming one of these real-life mermaids.