2046 saw a swift shift in global exports, attributed to the creation of a sturdy cardboard that could absorb 80% of shocks. This groundbreaking invention came to be the focal point of "Little Battler eXperience" or LBX, a favorite pastime for children. Four years later, Yamano Ban, an avid LBX player without a mecha of his own, receives a mysterious case from a woman containing a model AX-00. He is informed that he now holds the fate of humanity in his hands, both its hopes and despairs.