The aging of Japan outweighs all other nations with the highest proportion of elderly citizens, 21% over the age of 65 in 2005. In 1989, only 11.6% of the population was 65 years or older, but projections were that 25.6% would be in that age category by 2030. However, those estimates are updated at 23.1% (as of February 2011) are already 65 and over, and 11.4% are 75 and over, now the world's highest (though 2010 Census age results have not yet been released). The change will have taken place in a shorter span of time than in any other country.

The age 65 and above demographic group increased from 26.5 million in 2006 to 29.47 million in 2011, a 11.2% increase. The Japanese Health Ministry estimates the nation's total population will decrease by 25% from 127.8 million in 2005 to 95.2 million by 2050. Japan's elderly population, aged 65 or older, comprised 20% of the nation's population in June 2006, a percentage that is forecast to increase to 38% by 2055.

This aging of the population was brought about by a combination of low fertility and high life expectancies (i.e., low mortality). In 1993 the birth rate was estimated at 10.3 per 1,000 population, and the average number of children born to a woman over her lifetime has been fewer than two since the late 1970s (the average number was estimated at 1.5 in 1993). Family planning was nearly universal, with condoms and legal abortions the main forms of birth control.

Japan ⁱ/dʒəˈpæn/ (Japanese: 日本 Nihon or Nippon; formally 日本国  Nippon-koku or Nihon-koku, literally the State of Japan) 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 Honshū, Hokkaidō, Kyūshū and Shikoku, together accounting for ninety-seven percent of Japan's land area. Japan has the world's tenth-largest population, with over 127 million people. The 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. In the late 19th and early 20th centuries, victory 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 parliament called the Diet.