Underground World

Underground World (地底世界) is a huge cavern that is as big as Dilhade and Azesion combined. It is cohabited by three great countries that are in conflict with each other.

Overview
The underground world consists of three nations, one holy city, and the dome. The dome is the canopy of earth that covers the underground sky—in other words, the surface. Due to being underground, there is no blue sky or sunlight, creating a food shortage. Despite this, other natural landscapes such as green plains, rivers, mountains, marshlands, deserts, and wastelands exist.

History
The cavern only came into being some time after Anos Voldigoad's death and reincarnation, so its existence and civilizations are unknown to him. Since it's impossible that such a complex structure could appear in just two thousand years, the gods are believed to be involved.

The first Selection Trial was held here, and that's how the people of the underground came to know about the gods. To survive the harsh conditions of their home, the draconids turned to them to survive. Eventually, three religions emerged, each with a kingdom founded upon it. Due to religious differences, the three nations waged war against each other.

Gaelahesta, the Holy Capital
A holy city that doesn't belong to any of the three great countries, and it's recognized as a neutral zone. Everastanzetta, the Institute of the Gods is located here, and it is accessible to anyone who wishes to learn about the gods.

Jiordal, Kingdom of the Divine Dragon
The country ruled by the Pope and followers of God.

Agaha, Kingdom of the Royal Dragon
The home of the Dragon Knights.

Gadeciola, Kingdom of the Supreme Dragon
A land without faith, those who enter must abandon it.