Aoi Umi no Tristia: Hontou no Takaramono

A coastal city once known for its beauty and role in maritime trade, Tristia fell into decline after a dragon attack. Despite the people's efforts to rebuild, their attempts only worsened the city's condition. In desperation, they turned to Prospero Flanka, a renowned inventor who had restored other failing cities. When Prospero finally arrived, only a single girl was present at the port to greet him. He had sent his granddaughter, Nanoka, in his place.