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, distant Taichun--at 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.