Peace in Miracle World, a kingdom ruled by the Queen Urara, was torn suddenly by the invasion of the “Scrap Empire” a realm of machines.

The Scrap Empire's leader turned all the citizens of Miracle World in animals. Being defenseless, the Queen was kidnapped.

Before being kidnapped, the Queen encommended Gray to find her little sisters and take care of the "Miracle Gem" a gem that is vital for the existence of Miracle World.