Long ago, a planet called Machina was home to a race of sentient machines known as Metal Cardbots. One day, the planet suddenly explodes, compelling its inhabitants to take up residence on Earth. To avoid drawing attention, the Cardbots disguise themselves as ordinary vehicles. In the present day, Jun, an elementary school student with a passion for BMX, accidentally uncovers the Metal Breath, a wrist gadget that enables him to capture and enhance the Cardbots with various abilities.