« Sponge cities ». New perspectives on the progress of urban de-growth in Japan

« Sponge cities ». New perspectives on the progress of urban de-growth in Japan

In recent years, preventing the relative and absolute decline of small to mid-size cities within national urban systems has become a top priority of many national agendas, even in France, where high birth rates and postwar regional planning policies aiming at balancing territorial development have for a long time concealed the extent of devitalization trends in smaller urban areas (Béal et al. 2017). Although they are still perceived as places of quiet urban life, the small to mid-size cities that are geographically and functionally remote from global urban networks are particularly concerned.

The decline of « non-metropolitan » cities has become an important matter of public interest in various countries ; it is tightly linked to rising worries about the unexpected effects of austerity budgeting imposed on public institutions. According to countless scientific papers or reports, territorial reforms and devolution policies inspired by New Public Management ideas played a major part in reinforcing development trends that distinguish global city-regions on one side, from shrinking urban or rural regions on the other. In the latter case, local resentment towards a perceived « abandonment » by central powers is thought to have exerted a significant influence on populist votes.  

Finding locally adapted solutions and giving a more nuanced vision of “territorial divides” have been important motivations behind the recent surge of academic literature that tries to analyse urban decline more systematically. Within this field, the place of Japanese case studies is paradoxical : their exploratory value is blurred by residually essentialist beliefs in the singularity of urban life in Japan.  As the first country to cope with a naturally decreasing population, Japan epitomizes all the challenges that await aging megacities and in particular, the so-called phenomenon of « sponge cities » (suponjika) : i.e. the perforation of local urban fabrics by residential or commercial vacant lots, such that daily living conditions and access to urban resources become more difficult for the remaining residents. Until the early 2010s however, attempts to build cross-national typologies of shrinking cities often insisted on the specificity of Japanese examples, especially the weight of the demographic factor and the apparent lack of social unrest in decaying urban areas.


On the « peripheralization » of urban decline in Japan

However, the release of geolocalized microdata by the Ministry of Internal Affairs (Sōmushō) and numerous partnerships between faculty departments and municipalities to conduct resident surveys, among other factors, have allowed for a finer – yet still fragmented – knowledge about uneven territorial development in contemporary Japan. Moreover, the contribution of Japanese or Japanese-speaking scholars to international congresses in urban affairs has not been left without notice : for instance, more than 8% of the papers presented at the 2018 International Geographical Union were focused on Japanese case studies, which can be seen as a will to bring back Japan into global urban studies’ perspectives, in a context of intensifying inter-urban competition worldwide. Empirical studies on the distribution of de-growth in Japan are now advocating stronger multi-level analyses that help question the consequences of market-oriented administrative reforms on inherited local urban governance. The interpretation of their results is also relying more than before on the contributions of interdisciplinary theoretical frameworks (sociology, political economy and political science). More articles, for instance, now insist on the long-term changes brought by the neoliberalisation of the Japanese Developmental State, when discussing the evolution of the country’s urban planning system (Hirayama 2005, Tsukamoto 2012) or how shrinkage affects peripheral cities and regions more strongly (Buhnik 2015, Abe et al. 2018). 

In particular, analyses of residential mobilities and of different segments of the housing sector show that losses of inhabitants and increasing rates of housing vacancy are much higher in rural regions and on the fringes of Japan’s main metropolitan areas. As illustrated by maps of demographical change by municipality and by neighbourhood in the Ōsaka region since 2000 (fig. 1 & 2), three kinds of dynamics can be identified within city-regions in spite of their complex organization :

1/ Low-densely inhabited urban fringes whose working-age population has massively emigrated and where “skilled returns” of individuals belonging to the 25-40 age group is perceived as too residual (for a significant revitalization of the agicultural sector, for instance) or temporary (to use the parental home as a holiday residence). 

Figure 1 : Population changes by municipality since 2000 (%), according to the results of national censuses. Source : Portal Site of Official Statistics of Japan (www.e-stat.go.jp). Map: S.Buhnik, 2018.


2/ Downtown neighborhoods, especially if they are close to or fastly connected to central business districts, have benefited from the implementation of large-scale renewal projects since the early 2000s. Situated in and around major railway hubs, these projects have drawn the construction of condominium housing around them, targeting small households of various ages. An increase in the number of married couples who raise their children in condominium apartments entails a recent rise in the population under 15 in metropolitan urban cores like Osaka city.   

3/ In-between outlying areas around Japan’s bigger cities during the XXth century, were developed to answer the housing crisis in the aftermath of the Second World War and to cater to the housing needs of a fastly growing population of white-collars (from the 1960s to 1980s especially). But their growth has become more sluggish, more fragmenter, and since the 2000s at least, globally negative for a majority of them. Two intertwined factors are particularly influential : a depreciation of housing stocks that is highly difficult to prevent (given the number of housing units reaching the end of their lifecycle) ; the fact that aging landowners whose children have left (« empty nesters ») are not sufficiently replaced by younger ones.  

Figure 2.


Fighting housing vacancy : what can local governments do ?

In Kansai for instance, the number of vacant houses (or vacant public housing units) reaches its peak in the areas surrounding Osaka city within a radius of 10-30 kms. According to the 2013 national housing survey of the ministry of Land, Infrastructures, Transport and Tourism in 2013, out of 8 millions of housing units left empty (13.5% of the national stock), roughly 3 millions were categorized as ownerless units : the inheritors, if there are any, have not inherited from the parcel and what is built upon it. Neighbors legitimately fear that badly maintained empty houses will further deteriorate land prices, at a time when said prices, in average, represent less than 15% of their purchase value, especially for houses bought during the 1980s-1990s (fig. 3).

Figure 3. Land prices evolution in Kansai, 2005-2015 (%) (average values are calculated for each reference point, based on information gathered by prefectural services).  Source : MLIT. Map : S. Buhnik, 2018.


Until the 1990s, the « land myth » (belief in continuously rising land values) encouraged households to take out a loan for land parcels that were remote from employment cores, albeit they were counting on an efficient commuting system (Aveline 2008). Moreover, the tax on built land is still 1/6th of the rate imposed on unbuilt land, a system meant to push households to construct a short-lived house that their heirs would replace when they would inherit the land. But many individuals born after the early 1970s, who graduated from universities at a time when labour market conditions had worsened, were not able to reproduce their parents’ lifecourse : marriage, housing purchase, forming a male breadwinner family model. The possibility to educate children in « greener » spaces, not far from their own parents’ home, still constitutes a powerful incentive to make an outward residential mobility. But as far as couple households are concerned, it is often less costly to purchase an unbuilt parcel rather than an already built land, which will also require to pay a heavy inheritance tax if it comes from one’s parents. Hence, heirs often prefer to rehabilitate their parents’ lot into parking spaces, a solution that municipalities, however, want to avoid.

Local governments, for a long time, had very limited room for manœuvre against inheritors who do not maintain a land with a house of poor quality that cannot be resold or simply renounce the inheritance. The Special Measure Law on Housing Vacancy (akiyato taisaku tokubetsu sochi hō), enacted in 2015, does not give a full pre-emption right to municipalities, but allows them to impose an added tax on empty houses deemed dangerous for the neighborhood. They can also dismantle empty houses and coerce the current owner or inheritor into paying for it, provided that he has the financial abilty to do so. In 2015, the dismantling of vacant houses at the expense of the owner has been ordered twelve times in total.


Sophie Buhnik,

Sophie Buhnik is currently member of the French Research Institute on Japan (at the Maison franco-japonaise) in Tokyo. She is also an associate researcher of the UMR Géographie-cités and the France-Japan Fondation (EHESS) in Paris. Her work focuses on residential and daily mobilities in shrinking cities in Japan (especially suburban areas and mid-size regional cities), and on the policies aiming at revitalizing them. The field studies upon which this article is based have received funding in 2017-2018 from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement N°645763, within the framework of the INCAS project.

Keywords : urban shrinkage, Japan, Osaka, suburban areas, aging (cities)