The by far most important means of public transportation in Japan are the trains. Aside from Tokyo and Osaka) the subway lives a shadowy existence and many times is even outclassed by the buses. Incidentally Hiroshima is the only town with a tramway.
The delightful thing with this concept is the fact that the trains are nearly always precisely on time: If the board display "Departure: 17:08 o'clock", well you better be sitting in the train at 17:08 or else its gone, however it doesn't leave one minute before either. Such a refreshing difference to our train system.
One fact is confusing the first few times: There's not one train line but thousands and thousands of them and nearly all are independent from each other and parts of different companies. In spite of that they all cooperate perfectly, the harmonize in a manner of speaking.