Adlivun, also known as Ryūgū-jō, is an underwater city located deep beneath the post-Cataclysm sea between Oreinashi and Shippuu in the middle of Yamato. It's the capital of the Merrow Empire and is ruled by Emperor Nootaikok and Empress Nerrivik. It has remained hidden from surface dwellers for centuries although its existence is alluded to in various folktales.