The housing system in Japan which formed after the Second World War was based on a modern family norm that led to the overwhelming provision of housing for ‘standard families’, consisting of an employed husband, a homemaker wife and two children. This system transformed the Japanese housing landscape to a great extent, though assumptions about ‘standard families’ have not necessarily corresponded to the actual residential practices of the Japanese. Current sociodemographic changes demonstrate a rise in non-conventional households together with an increasing diversity of lifestyles, which contradicts concepts of homogeneity and standardization, and may confl ict with dwelling design as well as housing systems developed for ‘standard families’.