When the world was at peace, the new demon lord came to power, disrupting all peace. In order to re-pacify the world, the Lord of the Immortal World came out of seclusion again and faced the Demon Lord. But he never figured out that this new demon lord was a madman... A new war was about to break out.
Later, the demon lord was asked why he did evil.
The Demon Lord replied: "You don't understand the evil I did..."
There is no reason for evil and good, it is just a miserable life.
Purpose: World peace