Adaptive reuse of vacant houses in Japan offers an innovative and sustainable solution to the increase in vacant houses. This approach aligns with principles of sustainable architecture and the circular economy by reducing waste, lowering energy consumption, and extending the lifecycle of existing structures. This study uses purposive sampling, analyzing 262 adaptive reuse cases across Japanese prefectures through partial surveys, municipal records, and online maps. K-prototype clustering identified three distinct patterns. Cluster 1 emphasizes modern businesses, such as food, beverage, and accommodation services, within urban areas to address the needs of densely populated regions and tourist hubs. Cluster 2 blends urban and rural contexts, balancing historical preservation with modern functionality. Cluster 3 highlights rural and scenic accommodations that cater to tourists seeking cultural immersion and authentic experiences, despite challenges like low population density and limited accessibility. These findings contribute to the theoretical understanding of adaptive reuse as a key strategy for repurposing underutilized spaces, promoting both economic and social resilience. In practical terms, it demonstrates how adaptive reuse advances circular economy objectives by preserving cultural heritage, enhancing environmental sustainability, and creating economic opportunities. Further investigation is needed to unlock the unexplored potential of adaptive reuse in broader contexts and functions.

Urbanization is an undeniable phenomenon that happens globally, including in Indonesia. Indonesian cities are growing, causing urban sprawl and transformation of rural areas into urban areas. In between the urban and rural there is peri-urban area that has unique mixed characteristics of both. Areas with such characteristics can be found easily in the outskirts of Bandung city. The growth of peri-urban areas in Bandung occurs simultaneously with the growing tourism industries. This phenomenon caused a spatial transformation especially to the existing houses, which gives impacts to the livability of the area. This article would focus upon how housing transformation in peri-urban areas can affect the livability of the area by using the North Bandung peri-urban area as a case study. The result shows that the spatial transformation that happens in peri-urban areas gives positive impacts to social, economy, and spatial aspects, but unfortunately not the environmental aspects.

Japan’s 8.5 million vacant homes (Akiyas) represent a paradox of scarcity amid surplus: while rural depopulation leaves properties abandoned, housing shortages and bureaucratic inefficiencies hinder their reuse. This study proposes AKI2ALL, an AI-blockchain framework designed to automate the circular repurposing of Akiyas into ten high-value community assets—guesthouses, co-working spaces, pop-up retail and logistics hubs, urban farming hubs, disaster relief housing, parking lots, elderly daycare centers, exhibition spaces, places for food and beverages, and company offices—through smart contracts and data-driven workflows. By integrating circular economy principles with decentralized technology, AKI2ALL streamlines property transitions, tax validation, and administrative processes, reducing operational costs while preserving embodied carbon in existing structures. Municipalities list properties, owners select uses, and AI optimizes assignments based on real-time demand. This work bridges gaps in digital construction governance, proving that automating trust and accountability can transform systemic inefficiencies into opportunities for community-led, low-carbon regeneration, highlighting its potential as a scalable model for global vacant property reuse.

In the global context, the phenomenon of urban shrinking has grown increasingly prominent in many cities. It poses challenges to urban planning and regional development, such as the occurrence of vacant houses. In the context of Japan, the demographic condition has substantially changed over the last few decades into a declining and aging population. The situation has been discussed in many articles as the main factor in the proliferation of vacant houses across the country. Regarding this issue, this study aims to examine the correlation between the age structure composition and the number of vacant houses according to the classification of vacant houses. The study employs quantitative analysis based on the official government data of vacant houses and age structure composition. The study found that there was a strong positive correlation between the age structure composition and the number of vacant houses. Furthermore, the study revealed that areas with a higher percentage of elderly residents tended to have a higher number of vacant house rates. Nevertheless, the investigation also revealed significant correlations with other age groups, indicating that vacant houses are not exclusively influenced by the elderly population but rather by a more intricate demographic landscape. Understanding the impact of age composition on vacant houses can help policymakers develop targeted strategies to address this issue. By focusing on areas with a high percentage of elderly residents, urban planners can implement initiatives to revitalize neighborhoods and reduce the number of vacant properties.