The beautiful and rich Danube Continent has three empires, the Irish Empire, the Normaton Empire, and the Knight Empire. These three empires are the existence of a city triangle that restrains each other. No one dares to start a war because they have a common enemy, the dark world. The power of the dark world is extremely huge. Anyone who comes out of the dark world can wipe out dozens of humans. Where there is darkness, there is light. The Holy City is the only force that can compete with the dark forces. Unfortunately, the number is too small. Therefore, every three years, young people with the most potential are selected from the three empires and recruited to the Holy City for training to resist the dark forces. Our story begins here.