Introduction

Japan was first proposed to be a “disparity society” in 2005. Today, almost two decades later, it is widely agreed that Japan is a society with wide disparities, a huge number of poor people, and many problems such as child poverty, unequal educational opportunities, poverty-induced crimes, and child abuse. However, long before the term “disparity society” was coined, some sociologists were already suggesting that disparity had begun to widen, and to begin empirical studies. Within sociology, the field that specializes in the issue of inequality is class and stratification studies, and researchers in that field were quick to recognize the importance of studying disparity in Japan. However, the trend of widening inequality had also been noticed in another related field: urban sociology. This is because the widening inequality began and progressed rapidly in metropolitan areas.