### Literature Review  
Past studies have examined the population drift and choice of residential locations. There are several approaches that can be employed to this end. One way to assess the population flow is by using census data. The total number or the ratio of people who moved into or out of each region is reported in the census. If the characteristics of each region are further examined, the factors that influence people's migrations (i.e., of the \"push\" and \"pull\" factors) can be determined by analyzing the relationship between the data for in- and out-migration. For example, [PERSON] and [PERSON] [18] assessed the reasons for and consequences of the residential choices of migrant younger elderly people versus older elderly people in the United States (US). Based on the gravity model, they found that, when choosing a destination for migration, the younger elderly are affected by moderate climates and policies (e.g., income taxes and welfare spending), whereas the older elderly leave their former resident states because of a high cost of living and property taxes. In Japan, a similar approach was conducted in some studies. [PERSON] et al. [19] described the dynamics of migration flows within the Tokushima prefecture, based on the utility gap of regions calculated from the statistical data (e.g., land price, the number of facilities) and the location of each city. The results indicated that the utility gap between the city areas and rural areas accounted for the population disparities. A series of studies by [PERSON] focused on the population flow patterns of local district scales in the Greater Tokyo Area, first by examining the entire population [20], and then by narrowing the subjects down to the young and productive age generations [21]. Both studies extracted multiple factors (e.g., accessibility to facilities, population density, and land use ratio) as well as the required development threshold that affected for each region's population growth. Their findings determined the factors that cause population disparity in each area. In addition, these studies also suggested that important factors that affected the propensity to migrate included the personal attributes of migrants. However, if only the net extent of the population flows among areas are used as indices, it is not possible to understand the relationship between people's motivations of migrant and living environments. This is because population data from censuses only provide the general results of population movements. Thus, we cannot judge whether individuals' migration is spontaneous one or not. To counter this problem, some studies used questionnaire surveys to elicit data about individuals' choice regarding place of residence, along with their disposition toward and their preferences for living environments. These data enable us to reveal the factors that affect spontaneous migration. An assessment of residential preferences is one of the approaches. Although many studies focused on the preferences of housing type, several studies included regional characters of the current places of residence. Some studies focused on the community (population) size and the locations of residence. [PERSON] and [PERSON] [22] examined the preferences for the community size and location and evaluated the satisfaction of residents in Texas. They found that the mismatch rate differed with the location of communities. By using survey data conducted in the US, [PERSON] et al. [23] focused on the people's preferences for and satisfaction with the community of current residences as the factors that affected the people's migration intensions. Their results indicated that preferences and community satisfaction were interrelated, and each had an independent effect on migration. In addition, [PERSON] and [PERSON] [24] examined not only the preferences for community size and location but also the living environments.