At one time, the world was suffering under Hadlar, the Dark Lord. That is, until peace was won back by Hero swordsman and his companions...
Time has passed...  Monsters liberated from under the demon king now live on Dermline Island, a solitary island in the south seas. 

A boy named Dai is the only human on the island.  He wants to become a Hero, and he's been living in peace with the monsters.  But his life is transformed when Hadlar is resurrected.

A promise to a mentor; encounters with companions; an unescapable destiny...  Young Dai begins his adventure to become a Hero, and to save a world once again in crisis!