The Japanese in Hawaii are the second largest ethnic group in Hawaii. At their height in 1920, they constituted 43% of Hawaii's population. They now number about 16.7% of the islands' population, according to the 2000 U.S. Census. The U.S. Census categorizes mixed-race individuals separately, so the proportion of people with some Japanese ancestry is likely much larger.

The Japanese diaspora and its individual members, known as Nikkei (日系) or as Nikkeijin (日系人), comprise the Japanese emigrants from Japan residing in a country outside Japan. Emigration from Japan was recorded as early as the 15th century to the Philippines, but did not become a mass phenomenon until the Meiji period (1868–1912), when Japanese emigrated to the Philippines and to the Americas. There was significant emigration to the territories of the Empire of Japan during the period of Japanese colonial expansion (1875–1945); however, most of these emigrants repatriated to Japan after the 1945 surrender of Japan ended World War II in Asia.