Kochi Castle is one of the 12 samurai castles with original keeps. Yamanochi Kazutoyo (Yamauchi Katsutoyo), who was granted Tosa Domain (modern-day Kochi Prefecture in Shikoku) after the Battle of Sekigahara in 1600, began constructing the castle and residence in 1601. The project took ten years, and the Yamanouchi clan remained at Kochi until the Meiji Restoration.
Kochi Castle makes excellent use of the land's layout. The Kagami and Enokuchi Rivers form a natural outer moat, with the castle perched on Mt. Otasaka. The main Honmaru bailey is situated on a rise to the south, with the Ni-no-Maru occupying the northern hill at a similar elevation. The Ni-no-Maru connects to the Honmaru via a corridor-like bridge called a roka-bashi across a small valley. Directly under the roka-bashi, blocking the valley, is the Tsume-mon gate. The layout deceptively suggests that the Tsume-mon is the entry to the Honmaru. However, any attacking enemy breaching this gate would find themselves heading away from the central precinct. While trying to breach the gate, they could be fired upon from the keep to their left, the gate above, and watchtowers to their right. Instead, entry to the Honmaru is to the right, up a flight of once heavily guarded stone stairs, through the Ni-no-Maru, and across the covered roka-bashi.
In 1727, many central structures, including the tenshu, were damaged by fire. Today, what remains is the rebuilt keep and palace from that period. The remaining tenshu was modeled on the original four-roofed, six-floor tower designed by Yamauchi Kazutoyo, who had wanted a mawarien, a balcony, and railing around the top floor. The reconstructed keep includes this feature. Around the bottom edge of the tenshu are tsuruge spikes called Shinobi Gaeshi, meant to prevent ninja and attackers from climbing the structure. These spikes are found only at Kumamoto, Nagoya, and Kochi Castles, with Kochi uniquely featuring trident-shaped spikes. Kochi Castle’s Honmaru Goten, the lord’s palace, is connected to the base of the main keep, a rare architectural feature. The living quarters occupy the first level of the main keep.
Kochi Castle’s Honmaru is particularly historically valuable, as it is the only castle with all its original structures—keep, palace, gates, and walls—still intact. A total of 15 structures designated National Important Cultural Properties remain at Kochi Castle, including the tenshu, Kaitokukan Honmaru Palace, Nando storehouse, nishi and higashi tamon yagura, Ote, Kurogane, and Roka gates, six wall segments, and the roka-bashi linking the Honmaru to the Ni-no-Maru.
See also
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Kaminoyama Castle
Kamino-yama Castle stood at the center of an important logistics hub, in the middle of the Yonezawa Plain, which served as the gateway to the western part of the Tohoku region. Roads connecting the Aizu, Fukushima, and Yamagata areas intersected here.
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Imabari Castle
Tōdō Takatora (1556–1630) served at different times as a vassal of several famous clans—Azai, Oda, Toyotomi, and Tokugawa. He took part in the Battle of Anegawa (1570), the Battle of Shizugatake (1583), the invasions of Kyushu and Korea, the Sekigahara campaign (1600), and the Siege of Osaka (1614–1615).
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Iwakuni Castle
Kikkawa Hiroie (1561–1625) was the grandson of the famous daimyo Mori Motonari and a vassal of the Mori clan. Under Mori Terumoto, he fought in both Korean campaigns and took part in the defense of Ulsan Castle. During the Battle of Sekigahara, Hiroie stood with his 3,000-man force on the side of the Western Coalition; however, even before the battle began, he sent Tokugawa Ieyasu a secret message stating that he did not intend to fight Tokugawa’s troops. As a result of his inaction, 15,000 soldiers under Mori Hidemoto were also unable to enter the battle, since Hiroie blocked their path.
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Gujo Hachiman Castle
Gujo Hachiman Castle is located on 350-meter Mount Hachiman, near the confluence of the Yoshidagawa and Kodaragava rivers, and not far from the Nagaragawa River. During the Sengoku period, this area was of great strategic importance: it stood at a key crossroads of routes connecting Mino Province in the south with the Sea of Japan in the north, and Hida Province in the east with Echizen Province in the west.
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Amagasaki Castle
The founding year of Amagasaki Castle is traditionally considered to be 1617, when Toda Ujikané built his castle here, making it the administrative center of the Amagasaki Domain. However, as early as the Sengoku period, a fortress built by the Hosokawa clan already stood on this site. After the fall of Itami Castle in 1579, Araki Murashige—formerly a vassal of Oda Nobunaga who had rebelled against him—fled to this earlier castle.
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Hiroshima Castle
Mōri Terumoto (1553–1625) was the grandson and rightful heir of the renowned Mōri Motonari. When Terumoto became the head of the Mōri clan in 1571, he inherited vast territories covering a large part of the San’in and San’yō regions in western Honshū. In addition, the Mōri clan possessed the largest and most technologically advanced naval fleet of its time.
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Fukuyama Castle
After the defeat of Toyotomi Hideyori’s supporters in the Osaka Campaigns of 1614–1615, many clans in Japan still remained not fully loyal to the Tokugawa shogunate, especially in the western Chūgoku region. Mizuno Katsunari (1564–1651), a cousin of Tokugawa Ieyasu, became the first of the Tokugawa house’s close retainers, the so-called fudai daimyō, to be relocated to this strategically important area.
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Tiba Castle
The founder of the Chiba clan is considered to be Chiba Tsunesige (1083–1180), who in 1126 moved his residence to the Inohana area and built a strongly fortified stronghold there. Although Tsunesige himself came from the Taira clan, the Chiba clan later supported Minamoto no Yoritomo, the future founder of the first shogunate.
