Additionally, the stations are generally owned by private companies—including the the development rights at the station. This means that the Japanese private rail companies capture a portion of the value created by the rail service, which otherwise would be an externality. So the companies have an incentive, as landowners, for rail ridership to stay high.
Some of them are, like the Shinkansen lines. Others are both owned and operated by private companies: https://en.wikipedia.org/wiki/T%C5%8Dkaid%C5%8D_Main_Line.
Additionally, the stations are generally owned by private companies—including the the development rights at the station. This means that the Japanese private rail companies capture a portion of the value created by the rail service, which otherwise would be an externality. So the companies have an incentive, as landowners, for rail ridership to stay high.