Long ago, the Emperor possessed great mystical powers... and now, a young boy wonders: will he have them as well. With no memories, and only a rose-shaped scar on his forehead as a clue, he ponders his legacy while on the run with the girl who rescued him from a group of armed warriors. She takes him to a scientist who seems sure Rose is the Emperor's clone, and that this young boy must assume the mantle of leadership. But opposing forces have created another clone from the Emperor's DNA... and the struggle for power begins.

The story revolves around four main characters - regular old 10th graders, until they are chosen by a slip of Tatsuki's tongue to be the human masters of the ancient Four Gods! The four teens are chosen to battle and vanquish the servants of the Demon King, who has escaped from the celestial world to wreak havoc on Earth.