In 2046, a revolutionary reinforced cardboard with 80% shock absorption was developed, rapidly transforming global exports. This material would soon become the arena for a popular children's hobby known as "LBX" (Little Battler eXperience). Four years later, Yamano Ban, a boy who loves playing with LBX (though he does not own a mecha himself), receives a case containing the AX-00 model from a mysterious woman. He is told that he now holds the hopes and despairs of mankind in his hands.