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. Japan is divided into 47 administrative prefectures and eight traditional regions, and around 75% of its 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 world's 11th most populous country, second most populous island country, and third largest island country. Tokyo is the country's capital and largest city.

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.