Because of the density of population and the commuting time that can be extreme in the large metropolis in Japan, people have developed a very efficient system of queues on platforms.
You should not use your mobile phone on the train, have them on silent mode at any time. Imagine if everyone was going to call and shout!!
you should stand in line and wait for your turn to step in or out
you should walk on the left and not moan!
and the list goes on. the only surprising thing is that at peak hours, Japanese sometimes become ruthless just to squeeze in the coaches, you will get push, walked over, pushed out like a jack in a box!!