Maetel's Journey: Part Two
The trains having landed on the Wandering Planet's surface to rescue the two Maetels, Redril and Testuro confront two extremely alien-looking creatures who refer to themselves as "humans". When the aliens confirm to their satisfaction that Tetsuro, Redril, the two Maetels and the two Conductors are flesh-and-blood and not mechanized, they are permitted to return to the trains. As they prepare to lift off, the Conductors are seized by a pair of mechanical creatures with a shape resembling that of the two "humans" they encountered before. They demand that the two boys surrender their passes and allow them to take their place on the train.
Aired 05/03/1981EP 110 - Maetel's Journey: Part Two

Galaxy Express 999
After witnessing the death of his mother and being left for dead at the hands of Count Mecha, ten-year old Tetsuro Hoshino is awakened by a mysterious woman, Maetal. In exchange for only his company, Maetal offers him the ride of his life on the Galaxy Express 999. It is said that those who travel aboard the legendary train to the end of the line can receive a free mechanical body and with it, immortality.
Impoverished and alone, Tetsuro leaps at the opportunity and joins Maetal on a quest that will span the cosmos. As the Galaxy Express 999 makes its way across our solar system and beyond, Tetsuro is drawn deeper into a dangerous universe where peril lurks at every stop.
(Source: Discotek)