"Mainland Japan" (内地, naichi; lit. '"inner lands"') is a term used to distinguish Japan's core land area from its outlying territories. "Mainland Japan" was an official term in the pre-war period, distinguishing Japan proper from its overseas territories (外地, gaichi, lit. "outer lands") in the Far East, such as Japanese Taiwan, Japanese Korea, Karafuto, the South Seas Mandate, and the Kwantung Leased Territory. After the end of World War II, its usage became less common and lost its previous legal significance.
The term's literal Japanese meaning might best be translated as "inner Japan" or "inner lands". The term "mainland" is somewhat inaccurate since it usually refers to all or part of a continental landmass, rather than islands. In the pre-1945 period, the "inner lands" included the Japanese archipelago, itself including the Ryukyu Islands and other island chains to the south of Honshu. The "inner lands" also referred during 1875–1945 to the Japanese-controlled Kuril Islands and during 1943–1945 to Karafuto, the southern half of the island of Sakhalin.
