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July 2023

Cultural Article

Oshiro – Japanese Castles

by Shinichiro Tsuri


1. Background

Have you ever visited Japanese castles, called “oshiro” in Japanese? If you are interested in architecture or the history of Japan, castles may be one of the recommended spots to visit if you travel there.

While various types of fortresses have been built since ancient times in Japan, the number of castles significantly increased during the Sengoku period (15th - 16th century), in which independent feudal lords fought each other over their land and resources. Due to factors such as Ikkoku Ichijo Rei (Decree of One Castle per Province) in the Edo period (1603 - 1867) and bombing during World War II, most of the castles were destroyed and currently there are only 12 castles towers (called “tenshu”) remaining that were built before or during the Edo period.


2. Example of a Japanese Castle – Himeji Castle

Himeji Castle, which is in my hometown, was registered in 1993 as the first UNESCO World Heritage Site in Japan and is one of the most famous castles among the 12 mentioned above. Since a fort was built on the top of Himeyama hill located in Harima Province (southwestern part of current Hyogo Prefecture) in the mid-14th century, it has been rebuilt and expanded, and the castle we see today was mostly erected during major construction in the early 17th century.

Castle tower of Himeji Castle (by Shinichiro Tsuri)


Elements and Areas of the Castle

Speaking of Japanese castles, castle towers may come to mind first. However, castles typically consist of structures such as moats, (stone) walls, gates, and turrets in addition to castle towers. Territories bounded by moats and walls are called “kuruwa.” Himeji Castle has three layers of moats (the inner moat, middle moat, and outer moat) and kuruwas are surrounded by each moat (inner kuruwa, middle kuruwa, and outer kuruwa). The inner kuruwa, containing castle towers and the feudal lord’s residence, is the core of Himeji Castle. While the middle kuruwa was mainly assigned as the residences of upper- and middle-class vassals, the residences of lower-class vassals and townspeople were located in the area of the outer kuruwa, which formed the castle town of Himeji. The total area within the outer kuruwa surrounded by the outer moat reaches about 2.33 million square meters.


Castle Tower – Symbol of the Castle

A castle tower, also called “tenshu,” is symbolic architecture of the castle. While a castle tower in Japanese castles has a military function as a weapons store, its main purpose is to show wealth and power of the feudal lord. Himeji Castle has a coalition type castle tower comprising of a main castle tower and three small castle towers located on stone walls which are connected to each other with corridor turrets. Himeji Castle is often called “Shirasagi-jo” (White Egret Castle) since its elegant white body appears to be a flying egret.


Defensive Features

As a military facility, Japanese castles have not only beautiful appearances, but also many features to defend against enemies. For example, you can see a number of unique shaped holes in the walls of Himeji Castle. They are called “sama” (loophole), which allows defenders to fire on attackers with arrows and firearms without exposing themselves; rectangular ones are for arrows (called “yazama”), and round, triangular, and square ones are for firearms (called “teppo-sama”). The white plaster covering Himeji Castle is used to enhance its fire resistance in addition to providing an elegant white appearance. The route leading to the main castle tower is winding, just like a labyrinth; attackers are trapped by dead-ends and confused by a downward slope that gives the impression that they are going the wrong way. Furthermore, attackers are forced to slow down and be exposed to defenders by multiple gates including ones with a low ceiling arranged on the route.


Sama of Himeji Castle

( 姫路城の狭間(射撃用の穴) by Takobou is licensed under CC BY-SA 3.0 )


3. Castle and Imperial Palace

The Imperial Palace, located in the center of Tokyo, is the main place of residence for the Emperor of Japan. Whereas it is called the “imperial palace,” its features more closely resemble that of a feudal lord’s castle, as was explained above, such as moats, stone walls, and turrets. The reason this happened goes back to 1868, when Emperor Meiji moved to Tokyo from Kyoto following the Meiji Restoration. The Tokugawa shogunate was overthrown and their headquarters at Edo Castle turned into the new residence of Emperor Meiji. The original residence is still remaining in Kyoto, which is now called the Kyoto Imperial Palace – it does not have moats, stone walls, or turrets. It may be interesting to compare both imperial palaces in Tokyo and Kyoto keeping the features of Japanese castle in mind, if you ever have a chance to visit Japan.


The Imperial Palace

( Seimon Ishibashi Bridge, Imperial Palace, Tokyo by . Ray in Manila is licensed under CC BY 2.0 )


The Kyoto Imperial Palace

( Imperial Palace by Daniel Gerhard is licensed under CC BY-SA 3.0 )

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