They were created 10,000 years ago by God in the form of the a stone slab called the Monolith to kill each other in the Battle Fight, with the winner granted a wish to alter the world. The 52 Undead represented 52 different species and battled so they can wish for the species they represent to rule the Earth, while the Joker represented death. While the other Undead were sealed by the Monolith, the winner of that battle was the Human Undead and the world has been populated by humans ever since. In the present, human archaeologists discover the sealed Undead and a madden Hirose set them free by mistake. However, the new Battle Fight was a front for a sinister plot by BOARD's chairman. Developing Rider Systems based around the Undead, a Rider can defeat an Undead, forcing its Ouroboros buckle to open up with a Blank Card thrown at it to reseal the Undead.