Aoi Umi no Tristia  

Tristia - błękitna wyspa, Tristia del Profondo Mare Blu, Tristia of the Deep Blue Sea, Тристия, 發明工坊, 蒼い海のトリスティア

Tristia was once a thriving ocean city known for its beauty and role in maritime trade. It was often praised as "marine jewelry." However, that was many years ago. A dragon attack left the city in ruins, causing it to become desolate. Despite their efforts, the people of Tristia were unable to rebuild their city. At the end of their hope, they turned to a legendary inventor named Prospero Flanka for help. Prospero was known for reviving cities that had been destroyed. The day finally arrived when Prospero came to Tristia, but it wasn't him who stood at the port. Instead, his granddaughter, Nanoka, arrived on his behalf.