One of the major duties of the Japanese Army in Manchuria was to defend and
maintain the South Manchurian Railroad. Here I will show some badges given
to those soldiers and also some badges from the railroad itself.
The Rail Defense emblem has two varieties: One has crossed rifles
superimposed on (or sometimes behind) a railroad tie and the other has axes
and a tie. The former is a defense unit and the latter is an engineer unit, though
their duties no doubt overlapped at times.
The South Manchuria Railroad has a distinctive M mark and a railroad tie. In
Japanese this company is called Mantetsu.
Manchuria Defense Commemorative.
Showa 7 
Mantestu 30th Anniversary Commemorative Badge.
(founded in 1906, so this is from 1936)