A war broke down on earth, the war between Gods and Demons that disturbed the peace of Humans. The Gods and Demons suffered many losses within the war and so... They choose a worthy warrior or "chosen" from the human world and make them pledge their loyalty to the God or Demon. The "Chosen" fights for their side but die within their fight, a number of centuries passed and the war between Gods and Demons ended with a draw. They left earth but left "affinities" to half of the people in the world. Though the war did end, they still choose their "chosen". The Gods and Demons was not satisfied with the results of the war and thus a war have started once more. A great God mentioned 'The Prophecy... Will come... A human that surpasses a God and Demon... One day...' The prophecy told that there will be a human that will surpass a God and Demon and this human will already foretell the victor of this war.