Surrounded by sea on all sides, Japan is made up of numerous islands, including some 14,000 remote ones with a perimeter of 100 m or more. This makes it one of the world's largest island nations.
The baselines that define the outer edges of Japan's territorial waters and exclusive economic zones lie at its outermost edges, and many of them are geographically located on remote islands far from the mainland.
Japan's border islands play important roles like serving as the basis for defining its territorial waters and exclusive economic zones.
Chart Source: Geospatial Information Authority of Japan website, "Longitude and Latitude of Japan's Eastern-, Western-, Southern-, and Northernmost Points"
(https://www.gsi.go.jp/KOKUJYOHO/center.html)
The official website of the Tokyo Metropolitan Government