The main method of transportation in the submerged world is a submarine with precise navigation. The submarine abilities have advanced rapidly; however, technological advances in a lawless world have brought forth a new group of ambitious rogues. TWA, a weapon-manufacturing corporation, has established an entity known as the Meluguis Empire. The Empire has in turn organized numerous submarine fleets, and has raided resources and food from the remaining land. People who have grown tired of the exploitation have established the Allied Forces in order to confront the Empire.