Scattered across the Earth, hidden away in tombs and buried beneath the ground are ancient and mysterious relics enchanted with magic. Those who discover these relics gain the ability to summon a demon or spirit corresponding to it, the spirit demon they summon being theirs to command as their familiar.

As time went on all manner of strange supernatural creatures began appearing on Earth, causing havoc with their mischief, and so many people became Demon Hunters, relying on their familiars to combat the threat, or find ways to exploit it for their own gain…