A young boy from the long destroyed planet Filament.
The Boy from Filament, as the name suggests, grew up on Filament before it was destroyed. Before his untimely death, he and his mother vowed to work hard and save up enough money to buy mechanical bodies for themselves.
The young boy is a character in the Galaxy Express 999 series, which was created by Leiji Matsumoto, who is popular for theCaptain Harlock franchise and its related series. He makes his first appearance in Episode #30 "The Ghost World Filament". In the anime series, his design and creation are credited to Shingo Araki and Shigeru Kogawa respectively.
When his mother brings Tetsuro back to their home for the purpose of him exchanging bodies, the young boy refuses saying that he couldn't possibly take the life of a person with the same dreams as him. Because of this act, his mother decides to return Tetsuro to Maetel and the GE999 to continue their journey.