"舞台是日本的大正時代，名叫竈門炭治郎的平凡農村少年，靠著賣炭來維持一家的生計。某天他下山去賣炭，回家時天色已暗，好心的三郎爺爺便留他住了一晚。隔天他回到家卻發現家人全都遭到殘殺，只剩禰豆子身體還有餘溫，然而她似乎變得跟平常不太一樣？為了尋求拯救妹妹的方法，炭治郎踏上了斬鬼的冒險旅程。

In a distant future, Tetsuro is a human boy who wants his body replaced with a robotic one. This is possible, but to do so he has to reach the Immortal Planet onboard the space train Galaxy Express 999. Maetel, a beautiful and mysterious blonde woman dressed in Russian style, joins him in the long journey through space. Every episode sees our heroes arriving in a new planet's space train station.

故事主要講的是一對孿生兄弟上杉達也、上杉和也與青梅竹馬的隔壁鄰居淺倉南的感情和夢想。這種對青春、對勝利、對自己夢想勇敢追求和拼搏精神影響了一代年輕人。