Artemis of the Transparent Sea: Part Two
After being brought aboard the 999, Artemis reveals her history, how she departed her mother to acquire a humanoid machine body. Having to work to pay it off in a factory had its toll however, and she stole a ship and fleed. Artemis dies soon after and is brought to the heart of her mother, where she is absorbed into it. With Galaxy Railways headquarters planning to destroy the mother, Tetsuro cries out for them to not do it.
Aired 08/11/1979EP 52 - Artemis of the Transparent Sea: 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)