Taking the Goki-Shichido (Five Home Provinces and Seven Circuits of Ancient Japan) as a theoretical framework, this book examines shrinking Japan from a regional variation perspective by municipality along the ancient Tokaido, which comprises 15 provinces, and seven prefectures today. The study identifies the principal explanatory factors based on the small area data of e-Stat through GPS statistical software tools such as G-census and EvaCva, within a historical perspective. This historical knowledge helps in understanding the significance of the regional cultural heritage that remains in each municipality today. The book pays special attention to municipal variations within the same prefecture, presenting a completely unique approach from what other researchers have pursued. This volume studies two present-day prefectures along the ancient Tokaido for detailed analyses of the impacts of regional variations of population decline in Japan. They are Shizuoka Prefecture, made upof the former Tootoumi, Suruga, and Izu provinces, and Mie Prefecture, formed by the ancient provinces of Iga, Ise, Shima, and the eastern part of Kii as examples to show the impacts of municipal power on regional variations of shrinking Japan. The reasons for selecting these two prefectures of the ancient Tokaido are twofold. First, they are made up of a multiple number of the ancient provinces. Second, other prefectures that fall under the Tokaido have been studied in the previous works of the present author by adopting the same methods of analyses. Thus, by presenting unique analyses of regional variations on small municipal levels, with demographic variables, social indicators, and historical identities of municipalities in Shizuoka and Mie prefectures along the Tokaido, this book offers suggestions for effective regional policy to revitalize shrinking Japan to a sustainable one.