Let's & Go!! focused on Retsu and Go Seiba, two young brothers who recieve racing cars called "Mini 4WD" by Dr. Tsuchia. From there on, the series portraits those two boys, training and costumizing parts to later on participate on Japans Cup, where all of Japans racers enter to be the best of the best!

After the first season, Retsu and Go have now formed a team called "TRF Victorys" which Tokichi Mikuni, J, and Ryo Takaba are part of. Together, they aim for the World Cup. In this cup, teams from all over the globe enter. Some of the teams are, NA Astrorangers (Americans), Eisen Wolf (Germans), Rosso Estrada (Italians).

The story follows the life of Retsuya and Gouki, two brothers with the same objective as Go and Retsu, to race and win championships! The two new brothers are faced with various traps set by an evil organization...together, along with other friends, they try to enjoy their races as much as possible, showing off their competitive spirit and taking down any kind of evil that might put the sport they love so much at risk!