Demographics of Japan means the things that are true about Japan's population. The population of Japan is 126 million people, which is the tenth largest in the world. Most of the people in Japan live in cities and most live on the main islands of Honshu, Kyushu, and Shikoku. Most Japanese people are of Japanese descent, but there are also small amounts of people from other ethnic backgrounds living in Japan too. The median age of Japan is 47.2 years old, which means that half of the population is older than 47.2 years and half is younger. Japan also has one of the lowest birthrates in the world, meaning that not many babies are being born.