A Cross-Regional Reconnaissance of Residential Fragility Gradients in Japan From Kyushu to the Greater Tokyo Periphery

This working paper applies a previously published non-invasive residential fragility classification framework to a single continuous cross-regional transect of Japan, running from Fukuoka in Kyushu through the Setouchi corridor, the Keihanshin region, the Nagoya–Mino industrial belt, the Fuji Five Lakes and Hakone resort zone, central Tokyo, and the northern Kanto periphery. The purpose is not to deliver market data but to test whether a classification framework originally developed and empirically anchored in a Taiwanese residential cohort retains descriptive traction across a different national housing civilization. The method is explicitly that of single-observer qualitative reconnaissance: it generates hypotheses and a structured descriptive vocabulary, not statistically validated findings. The transect suggests that latent residential fragility in Japan is frequently more concealed than in less-regulated markets — not because the underlying risks are absent, but because a mature regulatory and certification regime displaces those risks into later, less legible, and more discontinuous failure modes. The paper proposes this pattern as “regulatory threshold blindness,” distinguishes it from ordinary threshold blindness, situates both within the established literatures on post-growth vacant housing, urban shrinkage, and seismic- certification policy in Japan, and offers a set of falsifiable hypotheses for subsequent quantitative work.