The Hokutosei, an overnight express train that runs between Ueno and Sapporo, will retire next March, it was learned Thursday.

The sleeper train is the last operating train of the Blue Train series, which gained popularity among sleeper train fans since its launch in 1958.

Sources close to East Japan Railway Co. and Hokkaido Railway Co., which operates the train, said the two companies decided to end Hokutosei operations because of its aging cars, and also due to difficulty in securing a line for the train when they are busy preparing for the shinkansen that is scheduled to start operating in spring 2016.

The train may be used during the sightseeing season as a special train, they said.

The Twilight Express, an overnight express train that runs between Osaka and Sapporo, is also scheduled to retire next spring.