In the year 372 of the Dakatide Era, the "Boundary Gap" a hundred years ago tore apart the Blue Star's crust. Tens of thousands of alien races poured in from the Gap. Humanity's thermal weapons system completely failed, and civilization was on the verge of destruction. In a desperate situation, human beings awakened their spiritual power and unlocked the "Kadao system" derived from the origin of the gap - using spiritual power to activate cards, summon war beasts, cast spells, and build defense lines, so as to gain the power to fight against alien races. Humanity entered the Kadao era.
The human territory is divided into seven major cities and hundreds of border abandoned cities. They are always facing the slaughter and erosion of alien races. The strong Ka Dao is the only support for mankind, and the person who stands at the top of the Ka Dao, can control Wan Ka, and protect the human race is respected as the "Ka Dao".
