Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asian mainland, it is bordered to the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea in the south. The Japanese archipelago consists of four major islands alongside 14,121 smaller islands. Divided into 47 administrative prefectures and eight traditional regions, about 75% of the country's terrain is mountainous and heavily forested, concentrating its agriculture and highly urbanized population along its eastern coastal plains. With a population of over 123 million as of 2025, it is the 11th most populous country. The country's capital and largest city is Tokyo.

The first known habitation of the archipelago dates to the Upper Paleolithic, with the beginning of the Japanese Paleolithic dating to c. 36,000 BC. Between the 4th and 6th centuries, its kingdoms were united under an emperor in Nara and later Heian-kyō. From the 12th century, actual power was held by military aristocrats known as shōgun and feudal lords called daimyō, enforced by warrior nobility named samurai. After rule by the Kamakura and Ashikaga shogunates and a century of warring states, Japan was unified in 1600 by the Tokugawa shogunate, which implemented an isolationist foreign policy. In 1853, an American fleet forced Japan to open trade to the West, which led to the end of the shogunate and the restoration of imperial power in 1868.

In the Meiji period, Japan pursued rapid industrialization and modernization, as well as militarism and overseas colonization. The country annexed Korea in 1910, invaded China in 1937 and attacked the United States and European colonial powers in 1941, thus entering World War II as an Axis power. After being defeated in the Pacific War and suffering the U.S. atomic bombings of Hiroshima and Nagasaki, Japan surrendered in 1945 and came under Allied occupation. Afterwards, the country underwent rapid economic growth and became one of the five earliest major non-NATO allies of the U.S. Since the collapse of the Japanese asset price bubble in the early 1990s, it has experienced a prolonged period of economic stagnation referred to as the Lost Decades.

Japan is a constitutional monarchy with a bicameral legislature known as the National Diet. Widely considered a great power and the only Asian member of the G7, it maintains one of the world's strongest militaries but has constitutionally renounced its right to declare war. A developed country with one of the world's largest economies by nominal GDP, Japan is a global leader in the automotive, electronics, and robotics industries, in addition to making significant contributions to science and technology. It has one of the highest life expectancies, but is undergoing a severe population decline and has the highest proportion of elderly citizens of any country in the world. The culture of Japan is globally well known, especially its popular culture, which includes art, cuisine, films, music, animation, comics, and video games.

The name for Japan in Japanese is written using the kanji 日本 and is pronounced Nihon or Nippon. Before 日本 was adopted in the early 8th century, the country was known in China as Wa (倭, changed in Japan around 757 to 和) and in Japan by the endonym Yamato. Nippon, the original Sino-Japanese reading of the characters, is favored for official uses, including on Japanese banknotes and postage stamps. Nihon is typically used in everyday speech and reflects shifts in Japanese phonology during the Edo period. The characters 日本 mean "sun origin", which is the source of the popular Western epithet "Land of the Rising Sun".

The name "Japan" is based on Min or Wu Chinese pronunciations of 日本 and was introduced to European languages through early trade. In the 13th century, Marco Polo recorded the Early Mandarin Chinese pronunciation of the characters 日本國 as Cipangu. The old Malay name for Japan, Japang or Japun, was borrowed from a southern coastal Chinese dialect and encountered by Portuguese traders in Southeast Asia, who brought the word to Europe in the early 16th century. The first version of the name in English appears in a book published in 1577, which spelled the name as Giapan in a translation of a 1565 Portuguese letter.

Modern humans arrived in Japan around 38,000 years ago (~36,000 BC), marking the beginning of the Japanese Paleolithic. Around 14,500 BC (the start of the Jōmon period), a Mesolithic to Neolithic semi-sedentary hunter-gatherer culture characterized by pit dwelling and rudimentary agriculture emerged. Clay vessels from the period are among the oldest surviving examples of pottery. The Japonic-speaking Yayoi people later entered the archipelago from the Korean Peninsula, intermingling with the Jōmon people. The Yayoi period saw the introduction of innovative practices including wet-rice farming, a new style of pottery, and metallurgy from China and Korea. According to legend, Emperor Jimmu (descendant of Amaterasu) founded a kingdom in central Japan in 660 BC, beginning a continuous imperial line.

Japan first appears in written history in the Chinese Book of Han, completed in 111 AD, where it is described as having a hundred small kingdoms. A century later, the Book of Wei records that the kingdom of Yamatai (which may refer to Yamato) unified most of these kingdoms. Buddhism was introduced to Japan from Baekje (a Korean kingdom) in 552, but the development of Japanese Buddhism was primarily influenced by China. Despite early resistance, Buddhism was promoted by the ruling class, including figures like Prince Shōtoku, and gained widespread acceptance beginning in the Asuka period (592–710).