Cities worldwide are urgently moving towards a more resilient and sustainable future. On this quest, national, regional, and local governments apply a combination of socio-spatial tools that regenerate and transform the city’s leftover spaces. There is an abundance of community gardens, cultural centers, and large-scale urban developments that, through programmed activities, reactivate underused spaces. The bearers of this process are professionals and individuals who have become aware of their actions in the contemporary urban landscape. This paper highlights possible design strategies that domesticate leftover spaces of diverse scales by injecting creative and playful programs, using Tokyo as a paradigmatic case study. More so than other global metropolises, the city represents a living laboratory for experimentation due to its compactness and the variety of urban patterns. Its leftover spaces demonstrate how play positively affects everyday life in public spaces, and how it enables extraordinary uses. A combination of ethnographic observations and spatial analysis is applied as a trans-disciplinary method. This approach allows an understanding of how people use playfulness to transform, appropriate, and utilize leftover spaces, which serves as guidance for urban planners and designers.

As cities navigate the challenges of commercial decline, suburbanisation, and demographic transition, night‐time urbanism has emerged as a critical yet underexplored dimension of sustainable urban regeneration. This article positions “night play” as both an analytical lens and a regenerative practice, foregrounding its potential to link cultural vitality, social inclusivity, and urban resilience. Two contrasting case studies are analysed: Tokyo’s Sangenjaya, a bottom‐up night‐time ecology of tiny alleys containing a network of small bars and eateries shaped by post‐war urban evolution, and Melbourne’s White Night festival, a top‐down, annual event attracting 500,000–700,000 visitors and generating a large urban economic impact. Through a mixed methodology of morphological analysis, embodied observation, discourse analysis, and urban policy review, the study compares emergent and curated forms of night‐time play, highlighting their differing logics, spatialities, and regenerative effects. Findings reveal that informal, embedded nocturnal economies facilitate sustained, small‐scale regeneration rooted in community and adaptive reuse, whereas planned, event‐led activations offer high‐visibility cultural and economic returns but risk temporal discontinuity and commodification of urban play. The research argues for hybrid approaches that combine the resilience of evolved nightscapes with the catalytic potential of curated events, positioning play as a tool for inclusive, culturally resonant, and sustainable urban futures.

This chapter offers a thoughtful reflection on the extreme condition of our future environment: the flooding of the world due to climate change and environmental abuse. Facing this emergency, our proposal seeks to investigate and speculate on one of the first floating cities experiments — the Metabolism of Kikutake’s Marine City (1958) — in order to propose a flexible and innovative floating typology and to propel insights about new floating ways of living. Imbued in a rising extreme “risk society”of a flooded world, or waterworld, we state the importance of the utopian speculation of the Metabolist movement as a provocative approach for investigating possible futures of the Anthropocene. <!----> <!----> <!----> <!---->

In a metropolis and metropolitan public space, increased attention has recently been given to overlooked and uncontrolled spaces. Considered as spatial 'voids,' 'idle spaces,' 'interstices,' and 'in-between' spaces, they all have one characteristic in common: 'the waiting for use' potential that can be ignited by users' creativity and tenacity, and with designers taking the role of 'enablers' rather than 'deciders'. Hence, urban leftover space becomes meaningful place with a strong local identity, enabling new connections and maximising its socio-spatial potential. This paper analyses Tokyo as a paradigmatic case study to investigate the roles of local spatial practices in the process of leftovers' identity (re)construction. More so than other global metropolises, the city represents a living laboratory for experimentation due to its compactness and the variety of small-scale urban patterns. A combination of ethnographic observations and visual analysis is applied as a trans-disciplinary method to investigate small-scale urban leftovers in Tokyo's traditional urban tissue of the shitamachi districts. This approach allows an understanding of how individuals transform and utilise leftovers, which become a dispersed constellation of tangible spaces of identity. Extrapolation of home into a public zone of liminal leftover space, through appropriation and care, becomes the key to the resilience of local identities.