From Nanshin: Japanese settlers in Papua and New Guinea, 1890–1949, by Hiromitsu Iwamoto (Journal of Pacific History, 1999), p. 10:
A MASSIVE EXODUS OF PEOPLE WAS A WORLD-WIDE phenomenon during the 19th century. About 50 million Europeans emigrated to the Americas and 47 million Chinese and Indians emigrated to the Asia-Pacific. However, the scale of Japanese emigration was small. Rough estimates of Japanese emigration before the Pacific War are at least 1.6 million: from 1868 to 1941, 776,304 Japanese emigrated to areas other than Manchuria, Korea and Taiwan, and from 1936 to 1940 about 820,000 people emigrated to Manchuria. Comparable figures were 23.1 million from Britain, 4.3 million from France, seven million from Holland, 33.9 million from Germany and 22 million from Italy between 1851 and 1950. The number of Japanese emigrants to Papua and New Guinea was tiny: it was never above 200.
The smallness of Japanese emigration is attributed mainly to Japan’s seclusion policy which prohibited overseas emigration until 1868 and its integration into world capitalism. Destinations for Japanese emigrants were limited, because by the time Japan began to modernise, most Pacific-Asian countries had been colonised by European powers. Although Japan’s rapid modernisation from the late 19th century with colonisation of Korea, Taiwan, Manchuria and Micronesia created space for emigration, this was only possible in a short period of 50 years ending with the Pacific War.
Japanese emigration to Papua and New Guinea began around the turn of the 19th century. It was an offshoot from the settlement of Japanese pearl divers on Thursday Island where they were squeezed out by Australian restrictions on migration and by the exhaustion of pearl beds. The migration was also a result of a series of searches for new beds and a place to settle by an adventurous Japanese skipper Komine Isokichi.