Bōsō Peninsula in the context of "Chiba Prefecture"

Kanagawa Prefecture (神奈川県, Kanagawa-ken; Japanese pronunciation: [ka.naꜜ.ɡa.wa, -ŋa.wa, -na.ɡa.waꜜ.keɴ, -ŋa.waꜜ-]) is a prefecture of Japan located in the Kantō region of Honshu. Kanagawa Prefecture is the second-most populous prefecture of Japan at 9,221,129 (1 April 2022) and third-densest at 3,800 inhabitants per square kilometre (9,800/sq mi). Its geographic area of 2,415 km (932 sq mi) makes it fifth-smallest. Kanagawa Prefecture borders Tokyo to the north, Yamanashi Prefecture to the northwest and Shizuoka Prefecture to the west.

Yokohama is the capital and largest city of Kanagawa Prefecture and the second-largest city in Japan, with other major cities including Kawasaki, Sagamihara, and Fujisawa. Kanagawa Prefecture is located on Japan's eastern Pacific coast on Tokyo Bay and Sagami Bay, separated by the Miura Peninsula, across from Chiba Prefecture on the Bōsō Peninsula. Kanagawa Prefecture is part of the Greater Tokyo Area, the most populous metropolitan area in the world, with Yokohama and a number of its cities being major commercial hubs and southern suburbs of Tokyo. Kanagawa Prefecture was the political and economic center of Japan during the Kamakura period when Kamakura was the de facto capital and largest city of Japan as the seat of the Kamakura shogunate from 1185 to 1333. Kanagawa Prefecture is a popular tourist area in the Tokyo region, with Kamakura and Hakone being two popular side trip destinations.

Izu Ōshima (伊豆大島, Izu-ōshima) is an inhabited volcanic island in the Izu archipelago and borders Sagami Bay and the Pacific Ocean, off the coast of Honshu, Japan, 22 km (14 mi) east of the Izu Peninsula and 36 km (22 mi) southwest of Bōsō Peninsula. As with the other islands in the Izu Island group, Izu Ōshima forms part of the Fuji-Hakone-Izu National Park. Izu Ōshima, at 91.06 km (35.16 sq mi) is the largest and closest of Tokyo's outlying islands, which also include the Ogasawara Islands.

Shimōsa Province (下総国, Shimōsa no Kuni; Japanese pronunciation: [ɕi.moꜜː.sa (no kɯ.ɲi), ɕi.moː.saꜜ-]) was a province of Japan in the area of modern Chiba Prefecture and Ibaraki Prefecture as well as the bordering parts of Saitama Prefecture and Tokyo (the parts that used to be located east of the lower reaches of the old Tone River prior to the river's eastward diversion, i.e. the parts of the former Katsushika District of Shimōsa that have been transferred to North Katsushika District of Saitama Prefecture and Sumida, Kōtō, Edogawa, and Katsushika wards of Tokyo). It lies to the north of the Bōsō Peninsula (房総半島), whose name takes its first kanji from the name of Awa Province and its second from Kazusa and Shimōsa Provinces. Its abbreviated form name was Sōshū (総州) or Hokusō (北総).

Shimōsa is classified as one of the provinces of the Tōkaidō. It was bordered by Kazusa Province to the south, Musashi and Kōzuke Provinces to the west, and Hitachi and Shimotsuke Provinces to the north. Under the Engishiki classification system, Shimōsa was ranked as a "great country" (大国) and a far country (遠国).