is an Edo Period Japanese castle in the city of Kōchi, Kōchi Prefecture, Japan. It is located at Otakayama hill, at the center of Kōchi city, which in turn is located at the center of the Kōchi Plain, the most prosperous area of former Tosa Province on the island of Shikoku. From 1601 to 1871, it was the center of Tosa Domain, ruled by the tozama Yamauchi clan under the Tokugawa Shogunate. The castle site has been protected as a National Historic Site since 1959, with the area under protection expanded in 2014.
History
During the Sengoku period, Tosa Province was dominated by Chōsokabe Motochika, who conquered most of Shikoku from stronghold at Okō Castle. However, Okō Castle was a mountain stronghold with little room for the development of a castle town. After his defeat by Toyotomi Hideyoshi in 1585, Motochika decided to construct a new castle at Otakayama hill and the ruins of an ancient fortification which had been constructed by Otakasa Matsuomaru sometime during the late Heian or Kamakura period. Although the new castle had the advantages of space and a central location, the area around the hill at this time was extremely swampy, due to the influx of alluvial sediments from the Kagami River, and was prone to flooding. Motochika shortly afterwards moved once again to a new location at Urado Castle on the coast, which also had the advantage of being closer to his fleet.
However, Motochika's successor Chōsokabe Morichika joined the pro-Toyotomi Western Army at the Battle of Sekigahara in 1600, and was subsequently deprived of his title, and later his life. The victorious Tokugawa shogunate ordered Yamauchi Kazutoyo, lord of Kakegawa Castle in Tōtōmi Province to take control of the province as daimyō of the newly-created Tosa Domain, with a nominal kokudaka of 202,600 koku. Kazutoyo first entered Urado Castle, but its defenses were weak, so he rebuilt Otakayama Castle from 1601 to 1611 on a larger scale. He renamed the castle "Kawanakayama Castle", and later changed the name to Kōchi Castle.
Much of the original fortress burned down in 1727; it was reconstructed between 1729 and 1753 in the original style. During the Boshin War, Kōchi escaped any damage, and the castle was also exempted from the post-Meiji restoration orders to destroy all remaining feudal fortifications.The castle also survived World War II unscathed, and underwent major restoration from 1948 to 1959. Though no battles were fought at the castle, it is noteworthy because the castle buildings are all historical structures, and not post-war replicas. It is also the only castle in Japan to retain both its historical tenshu, or keep, and its palace, the residence of the local daimyō. In fact, it is the only castle to have all the original buildings (from the 18th-century reconstruction) in the honmaru, or innermost ring of defense, still standing.
Kōchi Castle was listed as one of Japan's Top 100 Castles by the Japan Castle Foundation in 2006. The castle is a 20-minute walk from the JR Shikoku Kōchi Station.
Cultural Property Status
As one of only twelve castles with intact original main keeps in Japan, Kōchi Castle was formerly designated a National Treasure () before the 1950 National Treasure Protection Law (文化財保護法施) was enacted. After the law was passed, a number of surviving structures within the castle grounds were individually given National Important Cultural Property designations: