War Hymn of the Distant Horizon

To people, it seems that the brave is righteous and the devil is evil. The brave fighting the devil is like justice fighting evil. All of this is so reasonable. It seems that everyone in the human world thinks so. For them, the devil is an invader and an existence worthy of death. But, is the truth of five thousand years ago really just an invasion launched by the demon world against the human world? It seems that behind this, there is a history that will be remembered by people.