Upon defeating the Demon Lord, the eight heroes and their journey were engraved as the biggest historic events of the era. Freedom from the Demon Lord's grasp allowed civilization to expand into the demon continent and create a new city from it.
From that city, a new king was elected. Then, unknowingly the king has turned against the rest of the world along with five heroes under his command. New artificial race emerged to assist the new king plunged the world into chaos once more.
What Malicious Arts had the king uncovered to turn against the world? This calls forth a new age of heroes to fight against the old heroes.