Sequel of Dragon Quest Retsuden: Roto no Monshou set 20 years after Arus saves the world from the Demon Lord Imagine.

5 years ago, in an event known as "the Day of Loss," magic ceased to function. In the underground land of Alefgard, the people of the kingdom of Radatome vanished in a single night. The only survivors are Aros, the prince of the kingdom, and A-Kagi, a member of a group of bandits known as the Band of the Hawks, who infiltrated the castle that night to commit a robbery.

Aros, who becomes an amnesiac due to trauma, is raised in the care of A-Kagi and the Band of the Hawks. Years later, events lead him to depart from the Hawks and begin seeking out the truth behind "the Day of Loss"—as well as the whereabouts of his missing twin sister, who appears to be stealing sacred crystal orbs on the orders of a young boy who calls himself "Lamia."

Meanwhile, the companions of the hero Arus have been systematically eliminated by unknown parties...