When an army of monsters attacked the castle Camelot and forced the Emperor to resign, the whole country fell under their rule, and the Emperor's son Radius had to flee. But in his heart, the young prince still hopes to reclaim the land that is rightfully his, and to defeat the monstrous conquerors. With the aid of his best friend, the wandering monk Nova, and a female fighter Mirion, Radius begins his quest.

Last Imperial Prince is an action RPG that plays from a side view. Radius and his AI-controlled party fight enemies (who appear on set locations) in real time, using melee attacks and magic. The party members level up, learn new spells, can equip weapons and armor and buy items in stores.