The True Fire Rune is one of the five elemental True Runes and governs fire. It was once in the possession of the Holy Kingdom of Harmonia but was stolen some 50 years prior to the War of the Champions by the Flame Champion who would go on to use the rune in the Grassland's struggles against Harmonia.
The rune would go out of control during that conflict's final battle, decimating both forces and ending the war. After that, the Flame Champion would seal the rune away. 50 years later, the leader of the new Fire Bringer would unseal the rune and inherit the title of the Flame Champion. The True Fire Rune holds great power but is also very dangerous due to its ability to hurt friend and foe alike.