Money: many places don't accept credit cards, so take travellers' cheques to ensure a plentiful supply of Yen. Japan is a cash society, and it's safe to carry cash around. By all means take a major credit card too (Mastercard or Visa) as most big city department stores, hotels and restaurants willl accept them. For withdrawing cash from cash machines (ATMs), see getting cash.

International adaptor for electrical appliances: electric sockets in Japan are the 2-pin variety, so an international converter plug is needed. Your appliances need to be dual voltage, as the mains supply throughout Japan is 100V. Or take rechargeable/cordless appliances, for minimum hassle.

Small luggage: try to keep your suitcase as small as possible. The Japanese do a lot of travel within Japan, but with small suitcases. So the luggage facilities on trains are limited, and luggage lockers aren't very large either. A massive suitcase or rucksack could be a problem. A couple of smaller cases would be better than a large one.

Slip-on shoes: Bear in mind that it's the custom to take your shoes off when going indoors. So shoes which are easy to slip off and on would make life easier.

Photocopies of travel documents: (Passport, visa, air ticket, travel insurance) in case of loss.

Japan Rail Pass Exchange Order: Buy one in advance if you plan to travel around by train, as it offers great value for money for 7, 14 or 21 days travel on the whole Japan Rail network. You have to buy it outside Japan, before you go. So get one and don't forget to take it with you!