According to the distribution of the number of reported cases of robbery, most robbery cases are committed in metropolitan areas such as Tokyo and Osaka. However, according to the changes in the crime rate over the last 20 years, the rate of increase is high in prefectures around Tokyo and Osaka whereas the rate in Tokyo is below the national average rate, and such a "doughnut phenomenon" suggests that, viewed over the long term, robbery cases have been expanding to neighboring areas that contain bedroom suburbs for metropolitan areas. These neighboring areas are conveniently located to access metropolitan areas with high anonymity. Furthermore, the background factors for this phenomenon may be (i) the rapid increase in population, (ii) deterioration in crime prevention due to the increase in new residents who are indifferent to their communities, and (iii) the increase in people who go out late at night due to the emergence of entertainment districts and overnight stores along with urbanization, all of which have occurred in neighboring areas of metropolitan areas.
  Most of robbery cases committed by visiting foreign nationals have occurred in Tokyo and the number of such cases has been increasing significantly whereas, as a new trend, robbery cases by those with particular nationalities are spreading to areas other than Tokyo, such as Tokai area and North Kanto area.