Tokyo
Tokyo is Japan's capital and the country's largest city.
Tokyo is also one of Japan's 47 prefectures but is called a metropolis (to) rather than a prefecture (ken). The metropolis of Tokyo consists of 23 city wards (ku), 26 cities, 5 towns and 8 villages, including the Izu and Ogasawara Islands, several small Pacific Islands in the south of Japan's main island Honshu.
The 23 city wards (ku) are the center of Tokyo and make up about one third of the metropolis' area, while housing roughly eight of Tokyo's approximately twelve million residents.
Prior to 1868, Tokyo was known as Edo. A small castle town in the 16th century, Edo became Japan's political center in 1603 when tokugava laysu established his feudal government there. A few decades later, Edo had grown into one of the world's most populous cities.
With the meiji restoration of 1868, the emperor and capital were moved from kyoto to Edo, which was renamed Tokyo ("Eastern Capital"). Large parts of Tokyo were destroyed in the great kanto earthqake of 1923 and in the air raids of 1945.
Osaka
With a population of 2.5 million, Osaka is Japan's third largest and second most important city. It has been the economic powerhouse of the Kansai region for many centuries.
Osaka was formerly known as Naniwa. Before the Nara Period, when the capital used to be moved with the reign of each new emperor, Naniwa was once Japan's capital city, the first one ever known.
In the 16th century, Toyotomi Hideyoshi chose Osaka as the location for his castle, and the city may have become Japan's capital if Tokugawa Ieyasu had not terminated the Toyotomi lineage after Hideyoshi's death and moved his government to distant Edo (Tokyo).
Yokohama
With a population of over three million people is Yokohama Japan's second largest city. Yokohama is located less than half an hour south of Tokyo by train, and is the capital of Kanagawa Prefecture.
Towards the end of the Edo Period (1603-1867), during which Japan maintained a policy of self-isolation, Yokohama's port was one of the first to be opened to foreign trade in 1859. Consequently, Yokohama quickly grew from a small fishing village into one of Japan's major cities.
Until today, Yokohama remains popular among expats, has one of the world's largest chinatowns and preserves some former Western residences in the Yamate district.
Hiroshima
Hiroshima has been the principal city of the Chugoku Region for hundreds of years. After its construction in the 16th century, Hiroshima Castle was the most formidable fortification for miles. Today, Hiroshima is a vibrant city and home to over a million inhabitants.
When the first atomic bomb was dropped over Hiroshima on August 6, 1945, the city became known worldwide for this unenviable distinction. The destructive power of the bomb was tremendous and obliterated nearly everything within a 2 km radius. One of the few buildings that remained standing afterwards has been preserved; known today as the A-Bomb Dome, it is a monument to the bomb's dreadful power.
After the war, great efforts were taken to rebuild the city. Predictions that the city would be uninhabitable proved false. Destroyed monuments of Hiroshima's historical heritage, like Hiroshima Castle and Shukkeien Garden, were reconstructed. In the center of the city a large park was built and given a name that would reflect the aspirations of the re-born city: Peace Memorial Park.
Despite the legacy of the bomb, Hiroshima has very much become a modern city. The downtown area is filled with places to shop, eat, and otherwise enjoy oneself. Another testament to Hiroshima's vitality is the Mazda Motor Corporation, which is based in the city. Mazda has a large factory outside the city center that offers visitors a museum as well as a look at its cars being assembled.