According to Rhein, the Guardian of the Holy Fire, the King of the Fire Kingdom, must be the strongest person in the entire kingdom because he faces the greatest pressure. The entire kingdom's source feedback will eventually converge on him. If the King's strength is not strong, he cannot guard the Holy Fire. Once the Holy Fire extinguishes, everyone shall perish, and the kingdom will be destroyed.
Therefore, until the True King emerges, he should be the strongest in this kingdom.
It is possible to borrow the power of the Holy Fire as well.
More critically, according to Yanuo and Saint Longde's research, to some extent, the King's strength also affects the strength of the Holy Fire. If the King's strength is insufficient, the Holy Fire cannot fuse more Holy Fire Seeds. If the King's strength is long-term weaker than that of the Holy Fire, the powerful Holy Fire will gradually weaken, falling from high rank.
