In May 2011, the Japanese authorities eased the entry requirements to Japan for foreign tourists from 61 countries. Nationals of these countries and regions are not required to obtain a visa to enter Japan when the purpose of their visit is tourism. Upon entry, tourists are permitted to remain in Japan for a period of stay, the length of which depends on which country you are from. Information can be found on the Ministry of Foreign Affairs of Japan website.
Tourists from the UK can remain in Japan for up to 6 months for travel and leisure purposes without the need for a VISA.