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.