Once upon a time, on a planet far away, a drop of life fell from the sky, and so life was given to the Exo Planet. Life would flourish, and the people of Exo Planet would live a prosperous life in one of the thirteen kingdoms that will eventually be established. Life would go on, and so will death. But the prophecy foretells a time when darkness will rise, on not only the Exo Planet, but also another planet possessing life, in a different galaxy. And so, just like always, when darkness rises, heroes shall also rise to battle it. The day will come when twelve heirs will be born to the thrones, to fulfill their destiny and fight to make things right once again. This is their story. The story of those twelve princes.