Japan /dʒəˈpæn/ is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is sometimes referred to as the "Land of the Rising Sun".Japan is an archipelago of 6,852 islands. The four largest islands are Honshu, Hokkaido, Kyushu, and Shikoku, which together comprise about ninety-seven percent of Japan's land area. Japan has the world's tenth-largest population, with over 126 million people. Honshū's Greater Tokyo Area, which includes the de facto capital city of Tokyo and several surrounding prefectures, is the largest metropolitan area in the world, with over 30 million residents.Archaeological research indicates that people lived in Japan as early as the Upper Paleolithic period. The first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other nations followed by long periods of isolation has characterized Japan's history. From the 12th century until 1868, Japan was ruled by successive feudal military shogunates in the name of the Emperor. Japan entered into a long period of isolation in the early 17th century, which was only ended in 1853 when a United States fleet pressured Japan to open to the West. Nearly two decades of internal conflict and insurrection followed before the Meiji Emperor was restored as head of state in 1868 and the Empire of Japan was proclaimed, with the Emperor as a divine symbol of the nation. In the late 19th and early 20th centuries, victories in the First Sino-Japanese War, the Russo-Japanese War and World War I allowed Japan to expand its empire during a period of increasing militarism. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the atomic bombings of Hiroshima and Nagasaki. Since adopting its revised constitution in 1947, Japan has maintained a unitary constitutional monarchy with an emperor and an elected legislature called the Diet.A major economic power, Japan has the world's third-largest economy by nominal GDP and the world's fourth-largest economy by purchasing power parity. It is also the world's fourth-largest exporter and fourth-largest importer. Although Japan has officially renounced its right to declare war, it maintains a modern military with the world's fifth largest military budget, used for self-defense and peacekeeping roles. Japan ranks high in metrics of prosperity such as the Human Development Index, with Japanese women enjoying the second highest life expectancy of any country in the world and the infant mortality rate being the third lowest globally.