The sprawling city of Tokyo, officially designated by the Japanese government as a “Metropolis”, is situated in the southern Kanto region, roughly in the centre of the Japanese archipelago. Chiba Prefecture (a prefecture being more or less the equivalent of a county) and the Edogawa River lie to the east of the city, mountains and the prefecture of Yamanashi to the west, the Tamagawa River and Kanagawa Prefecture to the south, and to the north the prefecture of Saitama. The Greater Tokyo area is the largest metropolitan area in the world with a population of over 33 million, about a quarter of Japan's total population.

In June each year cold air from the north meets warm air from the south creating a rainy season or tsuyu, which literally means "plum rain" because it coincides with the season when the plums ripen. Although the rainy weather is not that inviting it can be a good time to visit Japan because there are less tourists, and some of Japan’s most typical outdoor attractions, such as temples, gardens and hot springs (onsen), are particularly appealing when seen in the rain.

As with most industrialised cities, the growth of businesses and administrative offices in Tokyo over recent years has had an impact on the environment with the disappearance of many green spaces. The population density in central Tokyo is over 13,000 inhabitants per square kilometre. The threat of earthquakes, and particularly the devastating fires that often follow them, is a constant worry, although modern Japanese buildings are built to withstand all but the most violent quakes.