The underwater city of Atlantis

"... The grand scale of it is practically a dream. A true Atlantis."
―Unknown explorer

Atlantis was a major settlement of sirens discovered by underwater explorers in the waters just off the north coast of Minami, believed to be the capital of the siren species. Some scientists speculated that the many strange occurrences that have occurred in the oceanic region originated from the sirens' extremely territorial protection of the city, though further research is needed to fully explain the significance of Atlantis. Although referred to as Atlantis, the city's true name remains unknown due to the complexity of the siren language.