Tetsuro Hoshino is a young boy who was born on Earth into poverty, and who wants nothing more than a machine body. He also wants revenge on Count Mecha, an evil man who was given a machine body and now hunts humans for sport, for killing his mother. As a street urchin, Tetsuro has no means to buy a machine body. However, he has heard that at the end of the Andromeda Galaxy, there exists a planet where such robot bodies are given away for free. All Tetsuro needs to do is get a pass on the Galaxy Express 999, the cosmic railway. And one day, Tetsuro meets the mysterious Maetel, who promises to give him her unlimited use pass for the Express on the condition that she be his travelling companion. Tetsuro happily agrees, and embarks with Maetel on an adventure across the stars. When Tetsuro starts out, he is every bit the whiny, immature, selfish child. However, the adventures he goes with Maetel on, the people he meets, and the sights he witnesses cause Tetsuro to slowly but truly grow into a strong, young man. Tetsuro also grows closer and closer to Maetel, and although the nature of their relationship might not be called romantic, they form a very strong bond of love. Though it is never explicitly stated, it is implied that Tetsuro is Captain Harlock's son. The evidence for this includes Tetsuro's mother saying that his father is alive but away for some reason, Captain Harlock's mysterious attachment to Tetsuro, and simple physical resemblance.

(Source: Wikipedia)