In the year 2024, young Shiki runs away from home to live with her grandfather, Taizou, who runs the Ushio Sea Service in the man-made island-city of Standard Blue. Four years earlier, Shiki's father died in a deep sea incident, and Shiki is now trying to learn about her father, herself and her family's deep connection to the sea. The Ushio's crew, gruff Takeshi and distant Taichunat, first consider Shiki a hindrance, but she wins them over with her enthusiasm and courage. When Shiki's mother comes looking for her, however, danger looms near and Shiki is put to the final test.