Getting one or two stops back on a train to catch an empty train constitutes fare evasion. Many commuters think it would not be found, but not necessarily true. This is what friends of mine working as station staff told me:
Ask all passengers to alight the train before it reverses
Make sure that all passengers queue up before doors
Do ticket inspection from the end of each queue
Result in penalty fares of 200k to 800k yen in most cases.
