If you stay in major cities in Japan more than 2 days, I strongly recommend you to get IC card.
You can charge money to the IC card and use it almost every time you take trains, subways, buses etc. It is very easy. You just touch it when you go through a ticket gate. You can check the balance in a screen at the gate. You can save time because you do not need to check the fees and line up for getting tickets.
Each area has its local ID card like PASMO and SUICA in Tokyo, ICOCA in Osaka and in other areas like Nagoya, Kyoto, etc. You can use PASMO in Osaka and ICOCA in Tokyo (some train companies in suburb area do not accept IC cards so please check details on the website or just try touching and see if it works)
Where to get : in major Metro stations in Tokyo, major JR stations in each area
How to get : at Ticket Vending Machines (for kids, you need to go to office with your passport)
Price: deposit is 500 yen
Charge: 1000 yen – 10,000 yen
Refund fee: FREE (if you use Suica IC card from JR, you need some refund fee at some conditions)
In addition to trains, you can also use it at some Convenience stores, coin lockers, and drink vending
machines. It helps a lot if you have trouble about recognizing each Japanese Yen coin and has heavy purse during your trip.
for more information >>>