There were two different worlds.
The first one, There were ordinary humans, it didn't have any destruction what so ever. It only had wars before. But now people lived peacefully.
Compared to it's second world. Those who lived there had incredible powers, others can fly, use magic. The deties bowed to maintain it's peace.
They sent a Goddess to find those who were only chosen's to weild they're powers. The two worlds were both connected. That is if the first world gets destroyed, the second world will too. The Goddess found an organization that is powerful to weild the deities powers.
And those are the Grand Chase. The Grand Chase promised to