My elder sister opened the fairy tale book and started reciting.

Once upon a time, a long, long time ago, the demon king invaded the world. He started his conquest of the world with his formidable powers, eradicating five countries from the map and slaughtering tens of millions of people. Beginning from the north, the Demonic Army moved south and eventually reached the Empire. Having been watching the demon king's movements, the Empire finally made its move.