About ten thousand years ago, war between humans and demons erupted. It lasted about a century and its casualties were unimaginable. However, the first King of the Human realm made ten legendary heroes known as the Ten Cross Order. The ten cross 10 extremely powerful being that ended the war in their favor, eventually they were known powerful legends.
When the King fell ill, he stated a final message to the ten cross, "It is not over." Those words became their final mission and after the King's death, they begun their journey to find answers to the final message.
After 10,000 years, Arthfael Hovrey, a member of the order found something interesting in Mirage Academy of Magic which would lead to clues to their mission. However, demons emerged once again to initiate another war. Arth decided to once again group with the ten cross in order to fulfill the King's final message.