Over the last few decades, geographically and socially small communities, like neighborhoods and local communities, have been expected to assume public roles in post-welfare-state society. However, the meanings and structures of local communities vary across time and place. In Japan, local groups based on territorial bonds like residents’ associations have mostly organized local communities or chiiki (literally region or area in Japanese, but also a term for local community) in a geographically and organizationally hierarchical structure. However, voluntary organizations have also recently assumed roles in local communities (chiiki), and many studies suggest that changes in society, families, and individuals have weakened territorial bonding groups like residents’ associations. In this case, it is necessary to understand how the geographical and social characteristics of voluntary organizations differ from those of territorial bonding groups. Moreover, emerging voluntary organizations are less comprehended than territorial bonding groups in the way of how to assume role in local communities. This study explores how newer voluntary organizations overlay and affect existing local communities formed by territorial bonding groups like residents’ associations, by examining a local disaster volunteer group—Nagoya Midori Disaster Volunteer Network (NMDVN)—established in 2004, in Midori ward, Nagoya, Japan. First, this study traces how people join NMDVN and how the local disaster prevention activities have expanded. Second, the study considers how we understand the ways that NMDVN overlays and affects existing local communities.

Many members joined NMDVN after attending the local government’s training programs for disaster volunteering and disaster prevention. They had various motivations and triggers to attend the training programs and to join NMDVN. And, some of participants were not so much interested in disaster prevention activities. Rather, they were motivated by the opportunities to initiate local activities or to acquire knowledge or information about disaster (prevention) to improve other local activities. Consequently, these motivations have enriched NMDVN’s activities.

When NMDVN was established in 2004, mainly by some residents of Midori ward who had attended the local government’s training programs, it did not have any connection to local communities. Thus, disaster prevention activities were difficult to perform. However, NMDVN has successfully expanded its activities by collaborating with public institutions and local networks of members who had various interests rather than disaster prevention. Consequently, by these activities at the local or neighborhood level, NMDVN was able to reach people whom existing territorial bonding groups like residents’ associations, were unable to do. Furthermore, NMDVN’s activities cannot be categorized as a form of existing local activities, performed mainly by territorial bonding groups.

Finally, as for overlaying or affecting existing local communities (chiiki) based on territorial bonding groups, NMDVN complements these group’s activities to some extent, while it also conducts newer community activities based both on networks beyond territorial bounds and on existing local communities formed by territorial bonding groups. Additionally, NMDVN’s local activities have networked with its various voluntary activities in other places across the country. Therefore, these multi-layering or diversification of local communities should be also recognized as a movement linked to places beyond specific local communities.

Since the late 1990s, population recovery in the central areas of Japan’s major metropolitan areas has attracted the attention of many urban geographers who are especially interested in the development of condominiums and the attributes of residents in central areas. Even though the concerns of recent studies have concentrated on the development of condominiums in central areas and the decline of suburban detached housing areas, almost no detached housing provision in Japan’s major metropolitan areas has been studied since the late 1990s. Based on that background, this paper examines the geographic distribution and land use changes of detached housing development in the Osaka metropolitan area from the late 1990s and investigates the influence of the changes in socioeconomic conditions on housing development. This area is an advanced example of a shrinking major metropolitan area in Japan in both demographic and economic terms. The principal findings obtained from this study are summarized as follows.

Detached housing provision, which is assumed to be centrifugal, has actually shown a relatively large increase in the cities adjacent to Osaka and the peripheral wards within it since the late 1990s. On a more detailed scale, the increase in households in detached houses was mainly distributed within old built-up areas, which seem to have been urbanized before 1975. Some districts in such areas experienced population declines despite a considerable increase in the number of households in detached houses, creating a mosaic pattern of population change.

Focusing on detached housing developments in Osaka, closed or relocated businesses in industrial areas were converted on a relatively large scale in the northern and western sectors along Osaka’s loop line railway. On the other hand, housing, small businesses, and underutilized land parcels (including parking lots) were converted on a small scale in the southern and eastern sectors with characteristics of crowded residential areas and mixed-use residential and industrial areas. The land in these areas was often sold due to inheritance after the owner’s death, dilapidated housing, or business closures owing to the successor’s failure or deteriorating economic conditions.

Redevelopment in old built-up areas characterized as “inner city” or “urban sprawl” has played an important role in detached housing provision since the collapse of the bubble economy in the early 1990s. However, such small-scale, fragmented renewal in the areas of dilapidated housing and population decline did not necessarily lead to an increase in the local population. The population and housing life cycles in such built-up areas as well as such economic factors as the collapse of the bubble economy and industrial restructuring have influenced housing development. These findings suggest that the dichotomy of condominiums in central areas and detached houses in the suburbs is an insufficient basis for understanding contemporary urban housing provision.