Simple rules –
- No smoking (actually illegal)
The following are not legal rules but breaking them would make you stand out as an uncivilized foreigner…
- No eating anything
- No drinking anything
- No phones ringing (set to silent)
- No talking on the phone (so don’t phone anyone)
- No (loud) talking (in fact, don’t talk much at all)
But DEFINITELY ALLOWED ARE –
- Reading or watching your phone or tablet
- Closing your eyes
- Falling asleep
These are the rules for behavior on trains and subways in cities. On shinkansens (bullet trains) which speed between cities, the rules are the same except that eating and drinking are allowed. In fact, there is a food and drink trolley service that comes through each carriage. And there are vending machines. And you can use your phone if you go stand in the walkways between carriages.
Japan Tourist Tips 