The Chūbu region , Central region, or Central Japan is a region in the middle of Honshū, Japan's main island. In a wide, classical definition, it encompasses nine prefectures (ken): Aichi, Fukui, Gifu, Ishikawa, Nagano, Niigata, Shizuoka, Toyama, and Yamanashi.

Honshu , historically called Akitsushima , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separates the Sea of Japan, which lies to its north and west, from the North Pacific Ocean to the south and east. It is the seventh-largest island in the world, and the second-most populous after the Indonesian island of Java.