Interesting, I don't know much about Railway Uniforms, but the guard's cap looks continental. British passenger coaches then were of the compartment type, 5 a side with usually a corridor on one edge [ we didn't adopt the inferior open compartments until the 1970s/80s ].
So I'm thinking German [ note the camera make ], Swiss [ both with lakes rather than seacoasts ] or France. Maybe Japan, but unsure how many young ladies travelled alone [ possibly ] in western clothes in the 1920s.
Just read Railways are the most important means of passenger transportation in Japan, maintaining this status since the late nineteenth century. Right now ! Wiki
This is sadly not the case where they were invented...*
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Partly due to the semi-insane privatisation, breaking up a fairly incompetent national railway company into a lot of very incompetent private railway companies.