A soul. The complete amalgamation of a human being. The brighter the soul shines, the stronger the human is. When someone dies, their soul continues on as an animal that best represents them. That is how it has been understood for centuries. However, times change. And souls are changing. They're changing colors, forms, and powers. The discovery of this caused people to panic, and separated them into three separate Kingdoms- Kingdom of Animals, Kingdom of Light, and Kingdom of Shadows. Three different people, each from a different Kingdom. One is destined to die, one is destined to betray everyone, and one is destined to be more powerful than all who came before.
What happens when you find out that you are an heir to another kingdom and the one that you work in your whole life is not your kingdom? You have to please people and stop your kingdom from going to war with the other kingdoms. Along with help to restore the kingdom that you were sworn to protect til your last breath.