Cash & Wall Sockets
You won't need a lot of preparation — Japan is highly connected and everything runs smoothly, but a few things are worth knowing before you go.
Good to Know
Wall sockets are US style, 110V.
No need to tip anywhere, anytime. Makes everything so much easier.
Getting from the airport to wherever you want to end up isn't too complicated. The Getting Around section covers Tokyo (Haneda & Narita), Osaka (Kansai), Fukuoka and Kagoshima.
Credit cards are less likely to be accepted the further you get from the major cities. And it's sometimes hard to find ATMs accepting foreign credit cards, so you'll want to plan your cash logistics accordingly.
Bring cash. Getting hold of it while in Japan might require more logistics than you think, especially when venturing outside major urban areas. And quite a few places and taxis don't do credit cards.
Order a rental pocket wifi device to be sent to your hotel, or pick it up at the airport. If you don't have cheap roaming this is definitely somehing you'll want to do.
Pick a place to stay if you haven't already. Here are some decent hotel suggestions in Tokyo and around Japan.
Get a Rail Pass if your plan includes travelling across Japan by train. You have to get it before you enter the country.
Check for Japanese holidays. Hotel room availability is scarce, trains are packed and domestic travel gets more expensive during public holidays. You might want to check whether your travel plans coincide with Japanese public holidays.
Want to get a bit of a feeling going for what Japan is like? This collection should get you started blubb blubb blubb