Shinkansen Henkei Robo Shinkalion

Hayato Hayasugi, the train-loving son of a train museum curator, accidentally stumbles into his dad's secret research lab one day. Inside he finds the E5 bullet train. As soon as he enters, he hears an announcement that a mysterious enemy, the Bachigami, is attacking the city of New Saitama. Luckily, with the touch of his father's Shinca card, the bullet train he's in transforms into a mighty robot — the Shinkalion E5 Hayabusa. Hayato and other children will serve as conductors to pilot the Shinkalion. 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.

Synopsis from Anime News Network