Tokushima Prefecture in the context of "Ōnaruto Bridge"

The Kansai region (関西地方, Kansai Chihō; [kaꜜɰ̃.sai, kaɰ̃.sai tɕiꜜ.hoː] ) a.k.a. the Kinki region (近畿地方, Kinki Chihō; Japanese pronunciation: [kʲiꜜŋ.ki, kʲiŋ.ki̥ tɕiꜜ.hoː]) lies in the southern-central region of Japan's main island Honshū. The region includes the prefectures of Nara, Wakayama, Kyoto, Osaka, Hyōgo and Shiga, often also Mie, sometimes Fukui, Tokushima and Tottori. The metropolitan region of Osaka, Kobe and Kyoto (Keihanshin region) is the second-most populated in Japan after the Greater Tokyo Area.

Wakayama Prefecture (和歌山県, Wakayama-ken; Japanese pronunciation: [wa.kaꜜ.ja.ma, wa.ka.ja.maꜜ.keɴ]) is a prefecture of Japan located in the Kansai region of Honshu. Wakayama Prefecture has a population of 876,030 (as of 1 February 2025) and a geographic area of 4,724 square kilometres (1,824 sq mi). Wakayama Prefecture borders Osaka Prefecture to the north, and Mie Prefecture and Nara Prefecture to the northeast.

Wakayama is the capital and largest city of Wakayama Prefecture, with other major cities including Tanabe, Hashimoto, and Kinokawa. Wakayama Prefecture is located on the southwestern coast of the Kii Peninsula on the Kii Channel, connecting the Pacific Ocean and Seto Inland Sea, across from Tokushima Prefecture on the island of Shikoku.

The Seto Inland Sea (瀬戸内海, Seto Naikai), sometimes shortened to the Inland Sea, is the body of water separating Honshu, Shikoku, and Kyushu, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka Bay and provides a sea transport link to industrial centers in the Kansai region, including Osaka and Kobe. Before the construction of the San'yō Main Line, it was the main transportation link between Kansai and Kyūshū.

Yamaguchi, Hiroshima, Okayama, Hyōgo, Osaka, Wakayama, Kagawa, Ehime, Tokushima, Fukuoka, and Ōita prefectures have coastlines on the Seto Inland Sea; the cities of Hiroshima, Iwakuni, Takamatsu, and Matsuyama are also located on it.

Awa Province (阿波国, Awa no Kuni; Japanese pronunciation: [aꜜ.wa (no kɯ.ɲi)]) was a province of Japan in the area that is today Tokushima Prefecture on the island of Shikoku. Awa was bordered by Tosa, Sanuki, and Iyo Provinces. Its abbreviated form name was Ashū (阿州). In terms of the Gokishichidō system, Awa was one of the provinces of the Nankaidō circuit. Under the Engishiki classification system, Awa was ranked as one of the 35 "superior countries" (上国) in terms of importance, and one of the "middle countries" (中国) in terms of distance from the capital. The provincial capital was located in what is now the city of Tokushima.

Kōchi Prefecture (高知県, Kōchi-ken; Japanese pronunciation: [koꜜː.tɕi, koː.tɕi̥ꜜ.keɴ], locally [koː.tɕi]) is a prefecture of Japan located on the island of Shikoku. Kōchi Prefecture has a population of 669,516 (1 April 2023) and has a geographic area of 7,103 km (2,742 sq mi). Kōchi Prefecture borders Ehime Prefecture to the northwest and Tokushima Prefecture to the northeast.

Kōchi is the capital and largest city of Kōchi Prefecture, with other major cities including Nankoku, Shimanto, and Kōnan. Kōchi Prefecture is located on Japan's Pacific coast surrounding a large bay in the south of Shikoku, with the southernmost point of the island located at Cape Ashizuri in Tosashimizu. Kōchi Prefecture is home to Kōchi Castle, considered the most intact Japanese castle, and the Shimanto River, one of the few undammed rivers in Japan.

Awaji Island (淡路島, Awaji-shima) is an island in Hyōgo Prefecture, Japan, in the eastern part of the Seto Inland Sea between the islands of Honshū and Shikoku. The island has an area of 592.17 square kilometres (228.64 square miles). It is the largest island of the Seto Inland Sea.

As a transit between those two larger islands, Awaji originally means "the road to Awa", the historic province bordering the Shikoku side of the Naruto Strait, now part of Tokushima Prefecture.

Kagawa Prefecture (香川県, Kagawa-ken; Japanese pronunciation: [kaꜜ.ɡa.wa, -ŋa.wa, ka.ɡa.waꜜ.keɴ, -ŋa.waꜜ-]) is a prefecture of Japan located on the island of Shikoku. Kagawa Prefecture has a population of 949,358 (as of 2020) and is the smallest prefecture by geographic area at 1,877 square kilometres (725 sq mi). Kagawa Prefecture borders Ehime Prefecture to the southwest and Tokushima Prefecture to the south.

Takamatsu is the capital and largest city of Kagawa Prefecture, with other major cities including Marugame, Mitoyo, and Kan'onji. Kagawa Prefecture is located on the Seto Inland Sea across from Okayama Prefecture on the island of Honshu, which is connected by the Great Seto Bridge. Kagawa Prefecture includes Shōdoshima, the second-largest island in the Seto Inland Sea, and the prefecture's southern land border with Tokushima Prefecture is formed by the Sanuki Mountains.