In the distant future, humanity has found a way to live forever by purchasing mechanical bodies, but this way to immortality is extraordinarily expensive. An impoverished boy, Tetsurou Hoshino, desires to purchase a pass on the Galaxy Express 999—a train that travels throughout the universe—because it is said that at the end of the line, those aboard can obtain a mechanical body for free. When Tetsurou's mother is gunned down by the villainous machine-man hybrid Count Mecha, however, all seems lost. Tetsurou is then saved from certain death by the mysterious Maetel, a tall woman with blonde hair and a striking resemblance to his mother. She gives him a pass to the Galaxy Express under one condition: that they travel together. Thus, Tetsurou begins his journey across the universe to many unique planets and thrilling adventures, in hopes of being able to attain that which he most desires. Tetsurou Hoshino is a boy bent on obtaining an immortal mechanical body in order to take revenge against his mother's murderer, the machine man Count Mecha. However, due to the incredible cost of obtaining what he seeks, his only hope is to steal a boarding pass for the Galaxy Express 999, a space train that travels across the galaxy and whose final stop is a planet where the metal replacements are provided for free. After swiping a pass, Tetsurou is pursued by the police and ends up collapsing into the arms of a mysterious woman named Maetel, who closely resembles his mother. Once he awakens, she tells the boy that she will provide him entry onto the 999 as long as he agrees to travel with her. Accepting her proposition, Tetsurou boards the cosmic railway with Maetel and begins a journey across the galaxy.