The people who came to Rothstein, an ancient island with a beautiful climate and scenery, founded the kingdom of Rothstein under the leadership of the hero Oz. A few years later, the wise Sheila arrived, bringing prophecies of prosperity and disaster, calling on Oz to create an arena to discover heroes with superior fighting skills to guard Rothstein. At first, Oz was uninterested until a disaster struck. The prosperous city of Rothstein was invaded overnight by countless monsters with a bloodlust that turned it into an inferno. Oz rose to the occasion and led myriad warriors to kill them, and after months of bloody battles, the beasts were finally defeated. But they found a strange corpse among the dead bodies of the beasts, with a huge head, dressed magnificently and accessorised with ancient runes. Sheila, who knew the ancient language, read from the runes on the accessories that this body had come from the planet Solaris. These magnificently dressed chiefs were called Skywalkers, or Men of Ancestral Stars. They also noticed that when these monsters were killed, they would explode and release some MOHs. It was speculated why there were MOHs buried under Cybora. Could these so-called mines be battlefields where ancient ancestors fought and killed otherworldly monsters? And because the early people did not know how to use the MOHs, were they deposited over time, so the corpses went underground along with the MOHs?