10 years ago, a dragon suddenly appeared in the sky of the Kingdom of Axile and then began destroying the whole kingdom.Peoples and Adventurers unite themselves to fight the monster, but it's pointless. The dragon is too strong, even the strongest Adventurer can't defeat him.And then, the dragon destroyed the kingdom in one night and disappeared at the same time.People who call themselves the Dragon Slayer try to find the dragon, but there is no trace of it can be found.After that, the calamity was named as Night of Despair and Dragon called Dragon of Calamity