A valid passport and a return ticket is required by all visitors to Japan. Visas are not required by US or EU nationals for a stay of up to three months. Further visas and visas for other nationalities are issued at the local Japanese Embassy or Consulate and their exact validity and price varies widely with nationality.
Visa and immigration related enquiries should be directed to the nearest Japanese Embassy of Consulate:
Embassy of Japan 101 Piccadilly London W1V 9FN Tel: (020) 7 465 6500 Fax: (020) 7 491 9348
If you require UK representation while in Japan you should contact the British Embassy:
British Embassy No 1 Ichiban-cho Chiyoda-ku Tokyo 102-8381 Tel: +  (3) 5211 1100 Fax: +  (3) 5275 0346 email@example.com
There are also British Consulates in Osaka, Nagoya, Fukuoka, Hiroshima and Sapporo
The Japan National Tourist Organization is a source of tourist information for visitors to the country:
Japan National Tourist Organisation Heathcote House 20 Saville Row London W1X 1AE Tel: (0171) 734 9638 Fax: (0171) 734 4290