Hayato Hayasugi (his last name is a pun on the words for "too fast") and other children will serve as conductors to pilot the Shinkalion. The Shinkalion robots are various models of real-life Japanese bullet trains (shinkansen) that transform into robots to fight an unknown evil to protect the safety and peace of Japan.
The children must work together with the adults of the Shinkansen Ultra Evolution Institute (SUEI) to defeat a monster that looks like a jet black bullet train.
While cleaning his house, eight-year-old Elon finds a summoning device and scooter left behind by his brilliant scientist grandfather. While riding the scooter and wearing the summoning device on his wrist he gets into a dangerous situation. Just then, the Archean necklace his grandfather left behind starts lighting up and summons an ancient Infinite Warrior (a Metalion) named Leo. Leo saves Elon from danger, and develops a liking for Elon. The newly reawakened Leo is appalled by the unruliness of humans and is saddened that Earth’s energy had long been depleted. Leo explains to Elon how he’s a Infinite Warrior and used to be his grandfather’s friend. Leo asks Elon to help him find all the remaining Archean Stones to restore the Earth’s energy. Elon designs a stone detector and uses it to begin his journey with Leo. The pair set off in search of the stones scattered around the world.