Underwater, some distance off of the Ashijian Coast. Dominated by natural and artificially grown coral reefs. Domain extends from coastal waters to deep trenches to open sea for pastoralism. Very dark most of the year as the skies above the underwater kingdom are under a permanent storm belt called the Amagumo-no-Ikari. There are underwater villages and towns made of coral and rock.
Six races: Ryūjin, Samebito, Kanikō, Ebinin, Ningyo, and Shinnin (Atlanteans). Loose caste-by-race system, with the Ryūjin being the undisputed high feudal lords, the samebito the warriors, the shelled peoples a mix, and ningyo dominating wizardry (though only a few Ningyo are true mages; most are unremarkable). The Shinnin are new and almost all are settler-peasants. There are 268,600 citizens. 6% can be mustered effectively for a mixed-race army of 16,350 (including 50 Ryūjin and 500 Ningyo Onmyōji war-mages). Up to 10% (26,860) can be mustered by emergency conscription, but the extra peasant levies will be of poor quality. The caste-by-race system is soft, and a burgher class is slowly starting to emerge due to social mobility.
Food surplus (can be exported). Absurd amounts of copper from hydrothermal vents; small strategic reserve of tin for bronze-making. Iron and steel are scarce and reserved for military or high industrial use—half is salvaged from sunken ships ushered by ocean currents, the other half traded with the Shogunate. Metallurgy is difficult underwater but made easier with magic. High medieval-era commercialization and industry.
Tributary state/vassal of the Aishijian Shogunate, due to an ancient pact with the Shogun's clan, the origins and exact terms of which are unclear. In exchange for ocean-based resources and products, the underwater kingdom received tin, iron, and charcoal.
Against surface powers, very deep, especially due to the storm belt and the hostile underwater environment for land-dwellers.
The size of the Dragon Country's army and its economy means it is able to conduct complex military campaigns in its own defense. Offensive intelligence service is rudimentary and ad hoc, but demographic presence at all sea levels can be leveraged for territorial defense information (e.g., sirens kidnapping fishermen or sailors). Divination is practiced by Onmyōji but is most effective at home in the native magic environment. Its legitimacy as a fellow vassal of the Shogunate and a powerful yokai kingdom can be leveraged to material effect. The country lacks a navy (a seafaring war machine force).
The Dragon Country is able to send military assets to any coastal area on Aishiji and is able to supply them. Soldiers are at home in the sea and can forage for food in bodies of water very easily. Half of the army is amphibious (shark-folk, crab-folk, Ryūjin) and they can navigate or infiltrate major and minor waterways, canals, and rivers. Should the need arise, mages are able to perform provincial-level ritual spells to defend or attack enemy strategic areas (e.g., Water mages using frost to make a harsh winter even worse in a localized area, such as an army camp). Military units are exceptionally mobile in the sea, but crab-folk are noticeably slower on land. Officers are highly motivated and glory-seeking, and are known to take initiative due to bushido culture and predatory instincts, if prone to warlordism in occupied territories. Generals (Ryūjin) are very conservative unless put in a life-or-death situation, and will favor safe or personally-enriching strategies. Provisions for supplying an armed force deep into land have only been hypothesized. Coordinated attacks against navies with large, escorted warships have only been hypothesized, though the mechanics of breaching a hull are well understood from salvage work. Male prisoners of war can be converted easily by sexually aggressive majority-female military.
Magical yokai creature army, half-amphibious. Samebito Bushi are utterly devastating heavy infantry; Dragon Country doctrine and culture emphasize the rapid and decisive use of shark warriors to break enemy lines. 30% of the regular muster are shark warriors. Shelled peoples are hardy and difficult to push back. Ningyo and Shinnin warriors are average. Ningyo Onmyōji and Ryūjin magic provide tactical support from the company to the army-level. Against surface navies, ships can be suppressed by magic and grappling hooks can be used to board them. Alternatively, they can be drilled into from below and undermined. Ranged weapons have not been adopted yet.
Otohime is the main character of this faction but will not lead armies. Unnamed Ryūjin, and Shark or Crab generals will lead the military effort.