The Kantō region is a geographical region of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures: Gunma, Tochigi, Ibaraki, Saitama, Tokyo, Chiba, and Kanagawa. Slightly more than 45 percent of the land area within its boundaries is the Kantō Plain. The rest consists of the hills and mountains that form land borders with other regions of Japan.