Historically, cities have been places of intricate and dense relations between urban forms and social networks with natural forces and innovative practices constantly influencing each other. It is precisely this magnetic complexity of compact urban space with its endless possibilities that still attracts the rural population and gives rise to the megalopolis. Since industrialisation, the speed of urbanisation, population growth and technological progress has accelerated to unprecedented rates, resulting in exacerbation of many existing urban issues and emergence of new challenges. A vast amount of literature favours the thesis that the tools that urban planners, governments and public sectors have been using or have developed over the last two centuries are not only insufficient but also harmful to city sustainability. (Sassen, 2005) views uncovering urban interconnections as a way ‘towards understanding what our large cities are about today and in the near future, and what constitutes their complexity’. In this respect, the research proposes to explore whether synergistic outcomes could arise from observing the complexity of acute disadvantages, such as natural disasters, demographics and local potential, such as ineffectively used urban space, as opportunities to bring about urban improvement.

Commonly, in seismically active regions, earthquakes have major socio-economic and environmental impacts on densely urbanised areas. Strong ground motion often triggers further devastating disasters such as tsunamis or fire spread. Exposed to a collective risk, informal, densely built-up neighbourhoods of wooden buildings represent the most vulnerable areas. When poorly maintained or abandoned, they pose clear danger due to deteriorating construction and proximity to other houses of poor seismic and fireproof performance. (Hirokawa & Osaragi, 2016) state that ‘[c]ollapsed buildings typically have a higher probability of catching fire compared with buildings that have not collapsed’. Another example for collective damage is street blockage. Obstructed, narrow alleys block the way for emergency vehicles, complicate the evacuation process and become extremely dangerous zones due to concentrations of gas emissions, heat and falling objects. Finally, a highly urgent issue concerning areas exposed to cumulative damage risk is problematic evacuation. In many cases, existing evacuation zones are insufficient and inadequately located, whereas fire-prone sections along firebreak axes could easily provide a fire bridge to the adjoining neighbourhood.

Global climate change alters precipitation patterns in an unprecedented way, resulting in extreme weather conditions. Together with geological hazards, such as earthquakes and landslides, they form disaster chains that have increasingly negative impacts on people’s daily lives as well as urban development [(Baodeng, 2016); (Okazumi & Nakasu, 2015); (Shaw, 2014); (Sh & I, 2011)]. Human activities such as urban sprawl (Suriya & Mudgal, 2012), reduction of infiltration capacity of catchments (Adeloye & Rustum, 2011) and flood resistance infrastructure (Liao, 2012) frequently reinforce impacts of weather events involving heavy precipitation in cities and erode their resilience to floods. Similar to areas prone to earthquake and fire spread, a critical issue in case of a flood emergency is safe evacuation that requires advance planning and technical expertise. Inadequate or delayed evacuation can expose inhabitants to secondary hazards such as power outages and damage to electrical, communications and transportation infrastructure, inability to access food and fresh water, particularly in high-rise apartments, and sewage-contaminated floodwater (Lane et al., 2013).

Ageing population and shrinking households are listed as critical issues for a number of developed countries due to low fertility rates, increasing longevity and changing modes of social relations [(Cohen, 2003); (Baker et al., 2014); (Feng et al., 2012)]. This phenomenon poses major policy challenges to countries with increasing proportions of elderly population in social, economic and political effects [(Bloom et al., 2010); (Muramatsu & Akiyama, 2011)]. However, demographic diversity and strong family and neighbourly relationships are traditional sources of support for liveable, prosperous and resilient communities (Muramatsu & Akiyama, 2011), whereas monotony and homogeneity bear grave consequences for the environment. Surveys such as those conducted by (Uhlenberg, 2000) emphasise beneficial outcomes of age integration in our societies. Besides the issue’s social aspects, presence of varied demographic groups is highly correlated with disaster preparedness. Dense areas with population of mostly elderly people are much more vulnerable to natural hazards due to their impaired physical mobility, diminished sensory awareness, chronic health conditions or social and economic limitations [(Muramatsu & Akiyama, 2011); (Taira, 2008); (Lane et al., 2013)]. On the contrary, young adults possess stronger self-preservation instinct and tend to react more adequately in case of emergencies. Low household ratio is also linked to per capita expenditures and environmental impact. Informal settlements populated mostly by elderly couples have very low energy saving performance, high living expenses and ecological footprints. (Aoshima, 2016) claims that power usage increases with the decline of household members. ‘[E]lectricity consumption’, the author goes on, ‘of the 70 or older group totals [. . . ] 1.6 times as high as for the 29 or younger group’.

Decades of functionalism, zoning policies and large-scale car-oriented development at the global scale have resulted in an unattractive public realm and an impaired ability to experience the city. (Stahle, 2016) emphasises the significant role the ground floor plays in economic and social success of urbanities since ‘it determines 90% of the building’s contribution to the experience of the environment’. In this regard, numerous studies have concentrated on the possibilities for a paradigm shift towards human-oriented urban planning. The general conclusion they draw is that mixed-use urban landscapes and social inclusion are prerequisites for the prosperity of each neighbourhood. (Mikelbank, 2008) maintains that a ‘city of strong neighbourhoods breeds a confidence among households, businesses, developers, and community leaders that spills over into the city’s economy in general’. (Jacobs, 1992) famously advocates the necessity of diversity of uses and people as drivers of innovation and urban success and the failure faced by a community if that diversity is missing. Similarly, (Florida, 2005) for the ‘creative class’ highlights the power of open and diverse places ‘to attract greater numbers of talented and creative people—the sort of people who power innovation and growth’. The lack of such diversity, substantially enhanced by the presence of a passive ground floor and disproportionately large enterprises (Jacobs, 1992), is a two-sided problem. On the one hand, deteriorating and homogeneous living environments adversely affect quality of life and, as such, make the vicinity even less attractive for people of diverse age groups and social status. On the other hand, they majorly impact the physical and mental health of local residents (Krause, 1998), which sets a vicious cycle of social and economic stagnation.

In the context of today’s urban density and scales, vacancies in metropolitan areas can be considered the equivalent of wastefulness and weak planning systems. Yet, abandoned properties of various functions are a commonplace phenomenon in socially and economically distressed neighbourhoods. They have a destructive effect on their surroundings, draining social and economic capital (Mikelbank, 2008). Their negative impact concentrates largely on the ground floor, which, as a result, becomes passive, unattractive and non-lucrative. When abandoned, buildings also become easy prey for burglars. Because of their poor maintenance, insufficient infrastructure and low hygienic conditions, they are hard to rent or sell. Moreover, in close proximity to other non-reinforced structures, they constitute areas that are most vulnerable to natural disasters.

Junkyards, vacant lots and underused and neglected open spaces represent another destructive category of land use that grows in grey and/or marginal areas. Analogous to vacant buildings, their presence signals that the environment is too poor, with too little surrounding magnetism and too low land values to sustain other uses. Outdoor parking lots and depots, on the contrary, have the potential to be profitable enough to economically justify their place in diverse neighbourhoods (Jacobs, 1992). However, their dominant presence comes at the price of a number of quality of life and environmental issues. Existing large outdoor lots thin the city and harm the relationship between spatial forms and social interaction. Jacobs stated that ‘[t]he more downtown is broken up and interspersed with parking lots and garages, the duller and deader it becomes’. The glorification of the automobile, (Livesey, 2004) claims, has ‘severely altered the traditional street that had been carefully scaled to the pedestrian and pre-industrial forms of transportation’. It is widely known that cars, together with their required infrastructure, are also conducive to reduced disaster resilience, to worsening air and noise pollution, to overloaded traffic systems and rising commuting times, to reduced physical movement and to growing expenses and environmental costs, irrespective of the cultural and social context.

Cities are complex adaptive systems that constantly evolve and recreate. To that effect, every urban area, regardless of its political, economic and social state of affairs, wields potential for successful development. Depending on the context of the place, its potential can vary greatly but the potential often lies in the combination of the interconnectivity of local issues and resources. Clearly, factors such as location, heritage, nature, urban milieu, technology, fiscal capacity, private–public partnerships, civic engagement initiatives, education and health care can be invaluable assets for facilitating urban progress. Yet, addressing problems directly, thus finding possibilities for action in a positive direction, can flip the vicious circle into a virtuous one. For example, acknowledging informal urbanism as an innovative resource and taking a fresh glance at human-oriented planning (Brillembourg et al., 2005), seismic and fireproof reinforcement of houses as glue for restoring community relations, abandoned buildings as an opportunity to introduce new uses and enhance the economic viability of a neighbourhood, underused vacant lots and infrastructure as a chance to reclaim the public realm for its inhabitants (Stahle, 2016) and build flood resilience, even a natural disaster as an occasion to rethink and improve the built environment (The Human Scale[Motion Picture, 2012). (Faehnle & Tyrväinen, 2013) underline the importance of collaboration, which serves not only planning and decision-making but also worthy of the stakeholders’ effort. The resulting synergistic improve- ment among such mutually reinforcing practices possesses aptness for generating momentum with lasting urban improvement outcomes.

The name Hikifune is not an official postal address. Locals refer to the area of 2 Chome Higashimukōjima, 2 Chome Oshiage and 4 Chome Mukōjima, between the rivers Arakawa and Sumidagawa in Sumida ward, Tokyo, as the Hikifune Toko-Niyon district (in short, Hikifune). Even though the neighbourhood lies in three postal address units and consists of two neighbourhood associations, at a local cultural and social level, it functions as a whole. Moreover, cohesion of residents plays a crucial role in case of emergencies and the need for rapid evacuation. For these reasons this work refers to Hikifune as an entity. The key location of Hikifune station provides not only easy access to popular commuting and commercial destinations for residents in the surrounding area but also regional transit services connecting northern prefectures with southern parts of Tokyo city.

After being largely destroyed on three occasions during the twentieth century, most parts of central Tokyo were rebuilt according to new safety regulations (Nakamura, 2012). Sheltered from these destructive events, Hikifune, as part of the more conservative district east of Sumida River, has preserved its urban form without any effective subdivision control, following a plot-by-plot urban pattern until today. According to a

(council, n.d.), since 2003, a large-scale redevelopment project is underway and many high-rise residential buildings and commercial facilities have been completed southeast of Hikifune station. Tokyo Skytree, the largest enterprise within Sumida ward, has a massive economic impact on the district. Apart from that, the currently running Tobuline Railway Renovation Project anticipates renewal and seismic reconstruction of the Tobu line, including Hikifune station, while the Sumida ward 2010 master plan suggests developing Hikifune neighbourhood as a local commercial high-rise centre connected to the already progressing Tokyo Skytree area and, further, with the Asakusa district.

The neighbourhood shows characteristics of a superblock (Shelton, 2012), comprising high-rise buildings along wide streets and an interior of two-to-three-storey houses of an average 40-year lifespan lining the narrow alleys roji. Evacuation streets along the periphery combine cross-city traffic movement with commercial and disaster prevention functions, while the meandering network of roji between low-rise buildings maintains locals’ circulation. The superblock is dissected by a passing through Hikifune station railway in two parts. Cars are rarely used within the neighbourhood, and the majority of the local people prefer to walk or use bicycles, motorbikes or the train to reach their destinations. Their preferred routes are small and mid-width alleys. The superblock predisposes correlation among the buildings’ functions, locations and height. Observed data suggests that most low-rise buildings within the interior serve an exclusively residential function, whereas mixed-use buildings with a shop or a service on the ground floor can be found in areas with frequent pedestrian circulation. According to Sumida Demographic Institute (2006), almost 70% of working residents are employed or self-employed in fine-grained establishments along these axes.

(Shelton, 2012) describes the Japanese urban space as an opposition of ‘layers of [positive] insides and [conceptually empty] outsides’. Hikifune’s densely built-up fabric consists of multi-layered private positive spaces (uchi) and a negative leftover (soto). Commonly, the narrowest alleys are, actually, overlapping semi-private spaces that provide needed access to uchi. Juxtaposition of ‘separate but co-existing systems’ is another phenomenon of the Japanese urban landscape (Shelton, 2012). Infrastructure, shrines, abundant vegetation, electric poles, along with people’s presence, personal belongings, roller shutters, ground floor workshops, new and old, modern and traditional, ‘participate equally [. . . ] in the imagery of urban Japan’ and ‘result in an amorphous and more collage-like surface’. Most low-rise dwellings constituting Hikifune’s interior are heirs of traditional Japanese townhouses. During the post-war period, these areas of urban vernacular began to rapidly disappear and are currently subject to intense large-scale redevelopment pressures. They are deep and narrow two-to-, occasionally, three-storey buildings with a shop space at the front, which makes the ground floor along the roji very versatile, thus establishing constant exchange between outside and inside, (semi-) public and private and contributing to the street’s diversity. Due to limited space, the usual connection with nature takes place at a street level, as part of the (semi-) public realm.