Background and History of Oizumi
The following outline of Oizumi's history and profile of contemporary Oizumi is presented with permission from the town of Oizumi.
Oizumi officially became a town in 1957 when the town of Koizumi merged with the village of Okawa, and 1997 marked the 40th anniversary of this reorganization. Since being designated a "Capital Region Urban Development District" in 1960, the town has made steady progress in luring factories and improving its infrastructure, and it has now become one of the most important industrial towns in the entire Kanto region.
In 1941 the Ota-Koizumi airfield was completed, and after Nakajima Aircraft's Koizumi plant opened the following year, the area flourished as a munitions center.
After [World War II], the American military used these facilities, but in 1959 they were partly returned, and in 1960 the town was designated Capital Region Urban Development District. Since the town has actively pursued the creation of industrial parks, the subsequent industrialization has been remarkable. Many outstanding companies have moved in, primarily producers of electrical equipment and motor vehicles. At present, the town ranks second in Gunma Prefecture in terms of the value of manufactured goods shipped annually.
As of September, 1996, Oizumi had a total population of only
42,134, but the number of (registered) foreigners living in town
was 4,391. The proportion of foreigners thus exceeds 10%, which
is a slightly higher percentage than in Shinjuku, the ward in
Tokyo with the highest concentration of foreigners. Almost all
the foreigners in Oizumi are Latin Americans, mostly Brazilians
of Japanese descent. 
Oizumi is one of Gunma Prefecture's leading industrial areas, and when Japan's "bubble" prosperity reached its peak in 1989, the labor shortage became very serious. Young people were avoiding so called "3-D" (dirty, difficult, dangerous) jobs. It was Japanese-Brazilians who make up the shortage. One reason was that a change in the Immigration Law made it possible for non-Japanese citizens of second-or third-generation Japanese descent to obtain visas for up to three years to work in unskilled jobs. Another reason was the success of Oizumi's comprehensive system for integrating such people into the community (such as providing national health insurance). As a result, many Japanese-Brazilians came to [Oizumi].
[Today] Japanese-Brazilians all over Japan know Oizumi for
its many businesses and events that cater specifically to them.
For example, a samba carnival has been a regular part of the Oizumi
Festival since 1991, and it is now a familiar summer scene not
only among Japanese-Brazilians but among Japanese as well. 
Not only does the town of Oizumi
put a lot of effort into comprehensive social services, as a progressive
international city it is also working on wide-ranging exchanges,
including a sister-city relationship with Guarantinguetá
in Brazil's São Paolo State. It would not be an exaggeration
to say that, by providing their valuable labor and becoming consumers,
Brazilians are now the source of Oizumi's vitality.
From Oizumi Town A to Z Oizumi: Poketto Gaido
Planned and published by the town of Oizumi (October 1996)
Nikkei-Peruvian and Nikkei-Brazilian Background and History
Historical Overview of Oizumi, Japan