All My Friends Are Pirates

In the primeval age, the "Saint D River" on Saint Ding Island gave rise to the founding of the Kingdom of Alabasta. In ancient times, the ancient weapon "Pluton" was born on Shipbuilding Island. At some unknown point in history, the people of the Moon came to this blue planet because they lacked resources. Eight hundred years ago, the World Government was founded, and the World Nobles have lived high above the world ever since, in the Holy Land of Mary Geoise. They proudly proclaimed: "Our houses will endure forever, our dwellings will last for generations, and we will claim the land in our own names." Yet people cannot remain exalted forever, any more than beasts can escape death. Eight hundred years later, a transmigrator arrived. He looked around. "Flags go up and flags come down. I'm familiar with that!"

P.S. The original work focuses more on individuals than on society as a whole. For the setting, I've borrowed ideas from the Age of Exploration on Blue Star to flesh out some of the worldbuilding and help the plot unfold. This is the second book in the Laborer Trilogy.