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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Arato Castle
Arato Castle was built in 1524 by the Yamada clan under the orders of their overlord, Murakami, as a small mountain fort. Over time, it gained strategic importance and became a focal point in the conflict between two famous daimyō of the Sengoku period — Takeda Shingen and Murakami Yoshikiyo. This conflict turned the castle into one of the key fortifications in the struggle for control over Shinano Province.
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Tatsuno Castle
Tatsuno Castle is not a single fortification but rather a complex consisting of two parts: a mountain fortress located at the summit of Mount Keirozan and a flatland-mountain castle situated at its base. The mountain stronghold was built around 1499 by Akamatsu Murahide. During the Muromachi period, the Akamatsu clan was an influential family that, at the height of its power, controlled the provinces of Settsu, Harima, Bizen, and Mimasaka. Murahide’s ancestors were directly involved in the events of the Genkō War in the 14th century and in the subsequent establishment of the Ashikaga shogunate. However, by the 15th century, due to the process of gekokujō, the clan began to lose its position under pressure from rising families, including their former vassals—the Urakami and Bessho clans. In addition, the Akamatsu faced constant pressure from the Amago clan of Izumo Province.
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Takamatsu Castle
Takamatsu Castle was founded by Ikoma Chikamasa (1526–1603), who was appointed ruler of Takamatsu by Toyotomi Hideyoshi in 1587. The following year, Chikamasa began construction of the castle on the coast of the Inland Sea (Setonaikai), completing it by 1590.
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Sawayama Castle
During the Kamakura period, Sabo Tokitsuna, the sixth son of Sasaki Sadatsuna, built a fort on Mount Sawayama. This fort occupied a strategically important position because it allowed control over traffic along the important Tōsandō route, which was later known as Nakasendō. This road connected the capital, Kyoto, with the eastern regions of the country. Due to its location, the fortification held great military importance, and during periods of civil war it repeatedly became the site of fierce battles.
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Nadzima Castle
It is believed that the first structures on this site were built by Tachibana Akitoshi (?-1568), head of the Tachibana clan, a branch family of the Ōtomo clan, as auxiliary fortifications for Tachibanayama Castle. In 1587, Toyotomi Hideyoshi established control over the island of Kyushu and granted Chikuzen Province to Kobayakawa Takakage, one of the leading vassals of the Mori clan. Takakage began construction of a new castle on the site of the existing fortifications in 1588. The exact date of completion is unknown, but by the time the invasion of Korea began in 1592, the castle had already been finished, as records note that Toyotomi Hideyoshi stayed there overnight on his way to Hizen Nagoya Castle, which served as the headquarters of the invasion forces.
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Kubota Castle
The founder of the castle is considered to be Satake Yoshinobu (1570–1633). Yoshinobu was one of the six great generals of Toyotomi Hideyoshi. During the Odawara Campaign of 1590, he took part in the siege of Oshi Castle under the command of Ishida Mitsunari, with whom Yoshinobu developed a good relationship.
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Kavanhoe Castle
Kawanoe Castle is located on the small Wasi-yama hill near the port area of the Kawanoe district in the city of Shikokuchuo, occupying a central position along the northern coast of Shikoku Island. Kawanoe was also known as Butsuden Castle. The term “butsuden” in Japan refers to temple halls, and for this reason it is believed that a Buddhist temple once stood on the site before the castle was built. Due to its location at the junction of four provinces on Shikoku Island, Kawanoe held significant strategic importance and was repeatedly targeted by rival forces seeking military control over the region.
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Yokote Castle
The founder of the castle is considered to be the Onodera clan. The Onodera were originally a minor clan from Shimotsuke Province and served Minamoto no Yoritomo (1147–1199), the founder of the first shogunate. The Onodera distinguished themselves in battle against the Fujiwara clan of the Ōshū branch and were rewarded with lands around Yokote. Around the 14th century, the Onodera moved to Yokote as their permanent residence. Their original stronghold was Numadate Castle, but after a series of clashes with the powerful Nambu clan, they relocated their base to the site of present-day Yokote Castle. It was likely during this time that the first fortifications appeared at the castle.
