Japanese Overseas Migration Museum (JOMM), Yokohama, Japan JICA Website
The Japanese Overseas Migration Museum in Yokohama, operated by the Japan International Cooperation Agency, has a reading room with extensive holdings of overseas Japanese newspapers, community directories, secondary sources on Japanese emigration to the Americas, and several special collections.
Following World War II, an unlikely alliance of labor leaders, leftist politicians, and business leaders came together to advocate for postwar emigration projects. After their first meeting in 1947, at the Tokyo Industrial Club, Diet Member Matsuoka Komakichi formed the Overseas Emigration Association (海外移住協会). Occupation authorities banned emigration projects, despite several requests for labor migration from Brazil and Argentina and a movement among numerous prefectural governments to restart migration, presumably to foster the redevelopment of inbound remittance flows. In 1952 and 1953, the first postwar emigrant groups left for Brazil and prefectural migration advocates came together to form the Japan Overseas Migration Federation (日本海外移住連合会), with former Osaka Shōsen president Shōzō Murata as president. In 1954, the association was given official permission to pursue emigration projects to South America. Much of the financial backing for emigration projects in the early 1950s came from a $1.5 million loan Prime Minister Yoshida Shigeru received with help from John D. Rockefeller, 3rd. In 1955, these funds were used to found the Japan Emigration Promotion Co., which bought land in Brazil and other destination countries to sell to emigrants. The company operated until 1963, when the Ministry of Foreign Affairs founded the Japan Emigration Service. In 1974, this entity was absorbed by the Japan International Cooperation Agency.
JICA has posted 240 PDFs of official JICA reports regarding migration and a number of its institutional histories online (most published between 1950 and 1990): Link to Table of Contents
Several of these files detail JICA’s history : Japan Emigration Promotion Corporation [日本海外移住振興株式会社], 1962. PDF and Kokusai Kyōryoku Jigyōdan, Kaigai e no Michi: Nihonjin no Kaigai Hatten [海外えの道：日本人お海外発展], 1980. PDF
These files are a valuable resource, but were digitized quite poorly and can be difficult to read.
JOMM’s collections are catalogued and can be searched here: link
The library holds a wide array of reports about postwar emigration produced by the Japanese government covering financial issues and the significance of Japanese emigration for the nation’s development and cultural diplomacy.
At JOMM you can also find a large number of prefectural association histories, which are a very useful way to chart trans-local migrant networks.