Sigils are magical stones, believed to be gift from the Goddess to humans, with exceptional power that they can harness to help them doing many things from mundane chores to battling vile creatures. But as the research goes on, humans started to weaponize sigils as an instrument of war to conquer each other.
The continent of Uthradia was actually a whole continent that is ruled by great four great nations: Gelnica, Tenseika, Askara and Luxus. The four nations were able to coexist in a relative peace at first, but when the development of sigil as weapon reached its peak, they became hellbent to conquer one another which caused a great war that lasts for five years. This war caused the continent to be separated into pieces. Realizing this, the emperor of the four empires decided to form a peace treaty in which each of the emperor are free to develop their own empire without getting in the way of others. This treaty is able to make them coexist again peacefully. Until 50 years later, one of the nations seems had a intention to break the treaty to wage another war.
Derek was a fighter slave who lived in Western Gelnica, which is notoriously known for its noble who has tendency to treat their slaves exceptionally bad. Derek always been treated cruelly by his master and he was accepting his fate as a slave for as long as he remembers he had been a slave since he was born, but one day he got a chance to escape which lead him to a string of events that will change his life and the fate of all the four great nations.