Mobile local sim: 7 days or 14 days mobile data sim is good option which can be used for mobile internet and also can be used for voice calls.
Many operators there.. http://www.bmobile.ne.jp/payg_sim/travelers_to_japan.html
Some analysis on mobile cards: http://www.mondaiji.com/blog/japan/general/10240-sim-only-mobile-providers-in-japan
For short visit it is good option to buy JR rail pass for a week or 2, we have to buy 1 week before you reach Japan, so that they will post exchange pass to your address. this is only for tourist visa visitors.http://www.japantravel.co.uk/japan-rail-pass.html
My visit experience:
So far I found Japan is most efficient, friendly, quick, easy, cost effective. Visitor visa is just 5£ charge and service and flexibility to accept pending documents is very good.. they have called me twice next day and asked me to send some more documents by email and immediately called me and confirmed me to collect visa in 4 days.
Immigration is also very quick, even bag verification efficient. Even outside airport, finding information, bus ticket everything very clear information they provide.
Very punctual, bus timings even for destination in time.. Sastry was telling me that is always on time for every bus, train etc. traffic is also very regulated and people follow regulations and law at all levels. They do not violate in any circumstances, including personal emergencies. Following process, preplanning for everything, timing, strict discipline in following principles and time. It is really wonderful to see such culture.