Dragon Quest Retsuden: Roto no Monshou

After monsters possessed the king of Carmen seven years ago, the kingdom fell to the hordes of evil. The only survivors were the king's son, Arus, and the army general's daughter Lunafrea. Meanwhile, in the kingdom of Loran, a child is born and christened with the name "Jyagan," as per the orders of the Dark Lord Imagine. While Arus is honest and good, Jyagan is allied with the forces of evil. With the blood of the hero Roto coursing through his veins, Arus sets out with Lunafrea in order to defeat the monsters and restore peace to the world.

(Source: Wikipedia)