When it comes to recommended tourist spots in Kikuchi City, Kumamoto Prefecture, the Kikuchi Castle Ruins is a must-see. Did you know that there used to be a castle called Kikuchi Castle in Kikuchi City? It was built by the Yamato Imperial Court less than 20 years after the Taika Reform.
Today, at the site of the Kikuchi Castle ruins, you’ll find reconstructions of the original octagonal buildings and ancient granaries, cleverly designed by the people of that era.
Not only history enthusiasts (rekijo and rekidan), but even those who aren't particularly interested in history will undoubtedly feel as if they've been transported back to the ancient times taught in Japanese history classes.
Make sure to visit and experience the revival of this ancient mountain castle for yourself!
What is Kikuchi Castle?
Kikuchi Castle was one of the fortresses established by the Yamato Imperial Court across western Japan to defend against a potential invasion of the Japanese archipelago after their defeat by the combined forces of Tang China and Silla in the Battle of Baekgang (663) on the Korean Peninsula.
On February 27, 2004, the site was designated as a National Historic Site. Historical records of Kikuchi Castle appear as far back as the Shoku Nihongi, a chronicle compiled in the early Heian period, which underscores the long-standing heritage of this mountain castle.
Octagonal Drum Tower
At the Kikuchi Castle ruins, the remains of four octagonal buildings have been discovered—structures that are not found in other ancient mountain castles in Japan. This unique octagonal shape suggests that these buildings held special significance.
One such building, known as the Octagonal Drum Tower, served to signal time using the sound of drums. Additionally, it was also used as a watchtower to monitor for any invasions from the Tang-Silla allied forces.
The reconstructed octagonal drum tower stands 15.8 meters tall and is topped with roof tiles weighing approximately 76 tons in total.
Other Reconstructed Buildings
Rice Granary (Komegura)
A short walk uphill from the octagonal drum tower leads to a building known as the rice granary (komegura). This structure was reconstructed as a rice storage facility, based on its resilient architectural design—capable of withstanding significant weight—and the discovery of charred rice in the surrounding area.
The granary measures 7.2 meters in length and 9.6 meters in width. It is built in the raised-floor style to prevent moisture damage and features a clever mechanism called nezumigaeshi, or “rat guards,” to stop rodents from getting in. It’s a remarkable display of the ingenuity of ancient Japanese people, something often seen in history textbooks and now visible in real life.
Board-Walled Storehouse (Itakura)
Further up from the rice granary lies another structure that served as a warehouse for storing weapons and armor. This is the Itakura, a board-walled storehouse, reconstructed based on the remains of a raised-floor building supported by earth-set pillars.
A unique feature of the Itakura is that pillars were also placed inside the building, adding extra strength to support the heavy weapons. The reconstructed structure measures 6.9 meters in length and 12.0 meters in width.
The roof is thatched, and the walls are constructed using a method where wooden boards are slotted into grooves carved into the side pillars—a distinctive ancient technique no longer seen in modern construction.
Barracks (Heisha)
The site of Kikuchi Castle also features the remains of a relatively large building known as the barracks (heisha). The individuals who manned the octagonal drum tower to watch for incursions by the Tang-Silla allied forces were called Sakimori, or frontier guards.
The Manyōshū, Japan's oldest anthology of poetry, includes songs by these Sakimori, many written in dialects from the Kantō region, suggesting that these guards traveled great distances to patrol and defend the coastline of Kyushu.
The reconstructed barracks building measures 26.6 meters in length and 7.8 meters in width, and features include a board-covered roof, earthen walls, dirt floors, and top-hinged windows, reflecting authentic ancient construction methods that are rarely seen today.
Earthen Ramparts on the South and West
Earthen ramparts (dorui) are embankment-like walls made of packed earth, constructed to prevent the intrusion of people or animals. On the southern side of Kikuchi Castle, the ramparts were built using a technique where layers of earth were repeatedly piled and compacted to create a strong and solid wall. This method is known as “hanchiku” (rammed earth construction).
The western ramparts, in contrast, follow a natural ridge line resembling a horse’s back. Unlike the southern ramparts that relied solely on hanchiku for elevation, the western ones were constructed by first forming a base with packed soil, then applying additional hanchiku layers on top to achieve the desired height.
Haizuka Observation Point” and “Chōjazan Observation Plaza Rest Area
The Haizuka Observation Point is located to the south of the western ramparts. From here, you can enjoy not only views of Kikuchi Castle but also the surrounding scenery. On clear days, it’s a popular spot offering a panoramic view of Mount Unzen, situated beyond the Shimabara Bay.
The Chōjazan Observation Plaza Rest Area sits atop a small hill to the east of the Haizuka Observation Point. While it functions as a rest facility and is not enclosed by walls—making it easily accessible—the roof and pillars incorporate traditional ancient Japanese architectural elements, making it a visually appealing structure.
There is also a public restroom right next to it, making it a perfect place to take a short break during your visit.
Onko Sōseikan and Chōjakan
Heading further east from the Chōjazan Observation Point, you’ll find a facility called the Onko Sōseikan. This center offers educational displays—including panels and photographs—about the historical background of the era when Kikuchi Castle was established, as well as its architectural structure. Visiting the Onko Sōseikan after exploring the castle ruins helps you connect the landscapes of modern-day Kikuchi City with the past, deepening your appreciation of the area’s historical richness.
Adjacent to the north side of the Onko Sōseikan is a building known as the Chōjakan. This is a local product hall, where you can shop for souvenirs from around Kumamoto Prefecture. There’s also a dining area where you can enjoy dagojiru, a traditional local soup made with dumplings—a famous specialty of Kumamoto. Be sure to give it a try!
◎ Access
The ruins of the ancient mountain castle, Kikuchi Castle, are accessible by car from several major points:
• About 40 minutes by car from Kumamoto Airport
• About 20 minutes by car from Ueki I.C.
• About 45 minutes by car from KikusuI I.C.
When planning your visit, please refer to the website below and consider traveling by car for convenience:
Name: Rekishi Kōen Kikuchi-jō / Onko Sōseikan
Address: 443-1 Yonehara, Kikuka-machi, Yamaga City, Kumamoto Prefecture, 861-0425, Japan
Official/Related Website URL: http://kofunkan.pref.kumamoto.jp/kikuchijo/