A pusher is a worker who pushes people onto the train at a railway station during the morning and evening rush hours.
When they were first brought in at Shinjuku Station, they were called "passenger arrangement staff" , and were largely made up of students working part-time; nowadays, station staff and/or part-time workers fill these roles during morning rush hours on many lines is derived from the verb "osu" meaning "push", and the suffix "-ya" , indicating "line of work.