A groundbreaking 80 percent shock-absorbing reinforced cardboard was invented in 2046, significantly changing the world's exports. The reinforced cardboard would quickly become a battleground for a popular children's activity known as "LBX" (Little Battler eXperience). Four years later, a mystery woman gives a case holding the model AX-00 to a youngster called Yamano Ban who enjoys playing with LBX (despite the fact that he is not a mecha himself). He is told that he now bears humanity's hopes and fears in his hands.