Zeltana kingdom, and probably kingdoms nearby too (but we don't care since the story will focus only in this kingdom), had been under assaulted by the Black Dragon Riders for so many decades now. The Riders would destroy fortresses and barracks. Villages would be burnt, while people would be killed or captured and never be seen again.

The root of such evil lied in one of the most ancient archaeological site, the Ruin Castle, which had been discovered by a team of the Wanderers Guild. Many teams had been sent there to find out what it was, but none found much. Actually, the last team never did come back at all. Within the Ruin Castle, there stood a black marble statue, which had the power to possess anyone gazed into its eyes.

The Soul inside the statue would transfer into the person, who at that point would be called the Host. There was only one Soul in the Statue, and it would return into the Statue once the Host died. The Host, however, would immediately absorb the knowledge and abilities from the Soul. Nobody knew what the Soul was exactly, but it was later called the 'Valkyrie'. One reason was because the Host would recruit, or actually capture, more people into the service of the Black Dragon Riders.

The Soul had the ability to conjure a Slave Crown, which once put upon anyone's head, that person would obey the one who put it on. It's because of the power of the Jewel, located in front of the Crown.