For transportation in Tokyo, ‘Welcome Suica‘ is convenient for foreign tourists. It is an IC card valid for 28 days ( sold by JR East company ) and should cover subways, JR local trains, buses in Tokyo. You can buy it in ticket machines in Narita airport, Haneda airport, major stations such as Tokyo station in Tokyo but unfortunately only Japanese yen is accepted, credit cards are not available so far, you can choose how much to purchase between 1,000 and 10,000 yen. Also you can recharge money to your card in ticket machines if necessary.
