Thirteen card decks were created for thirteen kamen riders. They make contact with monsters from the mysterious mirror world a parrel dimension opposite to our world in which only the kamen riders can exist. The riders draw on their monsters strength in exchange for feeding them the life force of the creatures they destroy. The creator of the advent cards has only one rule: that can only be one Kamen Rider. The others must be killed, and sole the victor will be granted a single wish, which leads to a conflict known as the Rider War.
