Asuke Castle, situated in Aichi Prefecture, may have been modest in size, but it played a pivotal role in numerous battles. It stands as one of Japan’s earliest and finest examples of a meticulously reconstructed Yamashiro-type castle from the Sengoku period.
Perched atop a 301-meter high hill named Mt. Mayumi in western Mikawa (now eastern Aichi Prefecture), Asuke Castle was originally founded in the 15th century by the Suzuki Clan. In 1525, Matsudaira Kiyoyasu, the grandfather of Tokugawa Ieyasu, launched an assault on Asuke. He not only captured the castle but also assimilated the Suzuki samurai into the Matsudaira clan.
However, in 1554, the Suzuki clan severed ties with the Matsudaira when the formidable Imagawa clan attacked. Overwhelmed, the Suzuki surrendered to the invaders. Two decades later, in 1564, Tokugawa Ieyasu, leading a 3,000-strong army, reclaimed Asuke, reinstating the Suzuki clan as vassals.
The castle saw further turmoil when Takeda Shingen seized it with 25,000 samurai in 1571. Nonetheless, in 1575, Matsudaira Nobuyasu, Ieyasu’s eldest son, besieged and defeated the Takeda forces, restoring Asuke to Tokugawa control. Eventually, Asuke was deserted in 1590 when Ieyasu accepted Toyotomi Hideyoshi’s offer to govern the Kanto districts, prompting him to relocate his headquarters to Edo (present-day Tokyo).
Given its repeated sieges, Asuke Castle held strategic significance, guarding the vital Ina Highway, also known as the “Salt Route,” which connected Owari Mikawa (eastern Aichi) with Shinano (Nagano Prefecture).
Asuke Castle, perched on a steep, cliff-like hill, was encircled by rudimentary log fences instead of stone walls. Although its unique defensive features like the Sakamogi trees are no longer present, nearly all aspects of Asuke Castle have been faithfully reconstructed. From its simple watchtowers and basic living quarters to its stables and defenses, every detail reflects the authenticity of the original structure.
The Minami-no-Maru, the main southern bailey, resembles an open fan and was originally occupied by kitchens and living quarters, as evidenced by unearthed artifacts. It features a nagaya-type dwelling with an irori fireplace inside and a simple kitchen outside. A wooden bridge leads to a lookout tower, offering views of Kessoku Castle’s ruins, a satellite fortress within the regional communication network.
Atop the central Honmaru stands the Taka-Yagura, a two-story tower with wooden shingles for roofing and black protective boarding on the lower two-thirds of both floors. Adjacent to it is a narrow nagaya housing, built using mud-faced walls and wood panels, serving as a defensive structure.
The samurai maintained provisions of weapons, food, and water within the castle, with the Nagaya featuring a dirt floor containing salt, a vital resource during sieges. The castle walls, constructed using the wattle and daub technique, could be chipped open during sieges to access dried taro potato stalks for emergency use.
Below the castle lies the town of Asuke, which thrived as a post station along the Chumakaido route for transporting salt and other goods. Today, remnants of its past, including houses with blackboarded walls and warehouses with white earthen walls, adorn the townscape, evoking its defensive heritage.
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.
