When most Westerners think of castles, they naturally think of places like England and France; however, Japan, too, was a nation of castle-builders. In its feudal days, you could find castles in nearly every prefecture.
Castles in Japan were built to guard important or strategic sites, such as ports, river crossings, or crossroads, and almost always incorporated the landscape into their defenses.
- See also: Pre-modern Japan
Castles in Japan began as fortresses for military defense. They were placed in strategic locations, along trade routes, roads, and rivers. Though castles continued to be built with these considerations, for centuries, fortresses were also built as centres of governance. By the Sengoku period, they had come to serve as the homes of daimyōs (feudal lords), to impress and to intimidate rivals not only with their defences but also with their sizes, architecture, and elegant interiors.
The first fortifications in Japan were made primarily of earthworks, or rammed earth, and wood, the earliest fortifications made far greater use of natural defences and topography than anything man-made. These castles were never intended to be long-term defensive positions: they were built when they were needed and abandoned the sites afterwards.
The Yamato people began to build cities in earnest in the 7th century, complete with expansive palace complexes, surrounded on four sides with walls and impressive gates. Earthworks and wooden fortresses were also built throughout the countryside to defend the territory from the native Emishi, Ainu and other groups; unlike their primitive predecessors, these were relatively permanent structures, built in peacetime. These were largely built as extensions of natural features, and often consisted of little more than earthworks and wooden barricades.
The Heian period (794–1185) saw a shift from the need to defend the entire state from invaders to that of lords defending individual mansions or territories from one another. The rise of the samurai warrior class towards the end of the period, and various disputes between noble families jostling for power and influence in the Imperial Court brought about further upgrades. As factions emerged and loyalties shifted, clans and factions that had helped the Imperial Court became enemies, and defensive networks were broken, or altered through the shifting of alliances.
Fortifications were still made almost entirely out of wood, and were based largely on earlier modes, and on Chinese and Korean examples. But they began to become larger, to incorporate more buildings, to accommodate larger armies, and to be conceived as more long-lasting structures. Chihaya Castle and Akasaka castle, permanent castle complexes containing a number of buildings but no tall keep towers, and surrounded by wooden walls, were built by to be as militarily effective as possible, within the technology and designs of the time. Castle complexes became fairly elaborate, containing a number of structures, some of which were quite complex internally, as they now served as residences, command centres, and a number of other purposes.
The Ōnin War, which broke out in 1467, marked the beginning of nearly 150 years of widespread warfare (called the Sengoku period) between daimyōs (feudal lords) across the entire archipelago. Noble family mansions across the city became increasingly fortified, and attempts were made to isolate Kyoto as a whole from the marauding armies of samurai that dominated the landscape for over a century. Over the course of the Sengoku period, many mountain castles developed into permanent residences, with elaborate exteriors and lavish interiors.
The beginnings of the shapes and styles now considered to be the "classic" Japanese castle design emerged at this time, and castle towns (jōkamachi, "town below castle") also appeared and developed. In the last thirty years of the period of war, drastic changes occurred to bring about the emergence of the type of castle typified by Himeji Castle and other surviving castles along with the introduction of firearms and the development of tactics to employ or counter them.
Japanese castle-building was spurred by the introduction of firearms. Though firearms first appeared in Japan in 1543, and castle design almost immediately changed in response, Azuchi castle, built in the 1570s, was the first example of a largely new type of castle, on a larger, grander scale than those that came before, boasting a large stone base (武者返し, musha-gaeshi), a complex arrangement of concentric baileys (丸, maru), and a tall central tower. In addition, the castle was located on a plain, rather than on a densely forested mountain, and relied more heavily on architecture and manmade defenses than on its natural environment for protection. These features, along with the general appearance and organization of the Japanese castle, which had matured by this point, have come to define the stereotypical Japanese castle.
Azuchi castle's stone foundation resisted damage from arquebus balls better than wood or earthworks, and the overall larger scale of the complex added to the difficulty of destroying it. Tall towers and the castle's location on a plain provided greater visibility from which the garrison could employ their guns, and the complex set of courtyards and baileys provided additional opportunities for defenders to retake portions of the castle that had fallen.
Cannon were rare in Japan due to the expense of obtaining them from foreigners, and the difficulty in casting such weapons themselves as the foundries used to make bronze temple bells were simply unsuited to the production of iron or steel cannon. The few cannon that were used were smaller and weaker than those used in European sieges, and many of them were in fact taken from European ships and remounted to serve on land; where the advent of cannon and other artillery brought an end to stone castles in Europe, wooden ones would remain in Japan for several centuries longer. It was often seen to be more honorable, and more tactically advantageous on the part of the defender, for him to lead his forces into battle outside the castle. When battles were not resolved in this way, out in the open, sieges were almost always undertaken purely by denying supplies to the castle, an effort that could last years, but involved little more than surrounding the castle with a force of sufficient size until a surrender could be elicited.
The crucial development that spurred the emergence of a new type of defensive architecture was, thus, not cannon, but the advent of firearms. Arquebus firing squads and cavalry charges could overcome wooden stockades with relative ease, and so stone castles came into use.
Among the many castles built in the ensuing years was Hideyoshi's castle at Osaka, completed in 1585. This incorporated all the new features and construction philosophies of Azuchi, and was larger, more prominently located, and longer-lasting. It was the last bastion of resistance against the establishment of the Tokugawa shogunate (see Siege of Osaka), and remained prominent if not politically or militarily significant, as the city of Osaka grew up around it, developing into one of Japan's primary commercial centers.
The Edo period ushered in over 250 years of peace, beginning around 1600–1615 and ending in 1868. Edo period castles no longer had defense against outside forces as their primary purpose. Rather, they served primarily as luxurious homes for the daimyōs, their families and retainers, and to protect the daimyō, and his power base, against peasant uprisings and other internal insurrections. The general architectural style did not change much from more martial times, but the furnishings and indoor arrangements could be quite lavish.
This restriction on the number of castles allowed each han had profound effects not only politically, as intended, but socially, and in terms of the castles themselves. Where members of the samurai class had previously lived in or around the great number of castles sprinkling the landscape, they now became concentrated in the capitals of the han and in Edo. Meanwhile, the castles in the han capitals inevitably expanded, not only to accommodate the increased number of samurai they now had to support, but also to represent the prestige and power of the daimyō, now consolidated into a single castle.
All castles, along with the feudal domains themselves, were turned over to the Meiji government in the 1871 abolition of the han system. During the Meiji Restoration, these castles were viewed as symbols of the previous ruling elite, and nearly 2,000 castles were dismantled or destroyed. Others were abandoned and eventually fell into disrepair.
Imperial Japanese Army
Some castles, especially the larger ones, were used by the Imperial Japanese Army. Osaka Castle served as the headquarters for the 4th Infantry Division. Hiroshima Castle served as Imperial General Headquarters during the First Sino-Japanese War (1894–1895) and later as the headquarters for the 5th Infantry Division; Kanazawa Castle served as HQ for the 9th Infantry Division. For this reason, and as a way to strike against the morale and culture of the Japanese people, many castles were bombed during World War II. The main towers of the castles at Nagoya, Osaka, Okayama, Fukuyama, Wakayama, Ōgaki, among others, were all destroyed during air raids. Hiroshima Castle is notable for having been destroyed in the atomic bomb blast on August 6, 1945.
Reconstruction and conservation
During the early 20th century, new laws were introduced for the preservation of heritage. Local governments had a legal obligation to prevent any further destruction, and they had some of the funds and resources of the national government to improve on these historically significant sites.
By the 1920s, nationalism was on the rise, and a new pride was found in the castles, which became symbols of Japan's warrior traditions. With new advances in construction, some of the previously destroyed castles were re-built quickly and cheaply with steel-reinforced concrete.
While many of the remaining castles in Japan are reconstructions, and most of these are steel-reinforced concrete replicas, there has been a movement toward traditional methods of construction. Kanazawa Castle is a remarkable example of a modern reproduction using a significant degree of traditional construction materials and techniques. Modern construction materials at Kanazawa Castle are minimal, discreet, and are primarily in place to ensure stability, safety concerns, and accessibility.
Most of the 12 original castles are in areas of Japan that were not subjected to the strategic bombing of World War II, such as in Shikoku or in the Japanese Alps.
At the other end of the spectrum are castles that have been left in ruins, though usually after archaeological surveys and excavations have been done. Most of these belong to or are maintained by local municipal governments. Some have been incorporated into public parks. Others have been left in more natural state, often with a marked hiking trail. The grounds of some were developed with municipal buildings or schools.
Some castle sites are now in the hands of private landowners, and the area has been developed. Vegetable plots now occupy the site of Kaminogo Castle (Gamagōri, Aichi), and a chestnut orchard has been planted on the site of Nishikawa Castle, though in both cases some of the castle-related topography can still be seen, such as the motte or ramparts.
Finally there are the castle sites that have not been maintained or developed to any degree, and may have few markings or signs. Historical significance and local interest are too low to warrant additional costs. Castle sites of this type also include nearly every area marked "Castle Mountain" (城山 Shiroyama) on the maps of towns and cities across Japan. Because the castle was small or may have been used for a short time in centuries past, the name of the castle is often lost to history, such as the "Shiroyama" at Sekigahara, Gifu Prefecture, or the "Shiroyama" between Lake Shōji and Lake Motosu near Mount Fuji, Yamanashi Prefecture. In such cases, locals might not be aware there ever was a castle, believing that the name of the mountain is "just a name". Detailed city maps will often have such sites marked. At the site, castle-related landscaping, such as ramparts, partly filled wells, and a leveled hilltop or a series of terraces, will provide evidence of the original layout of the castle.
Many castles across Japan serve as history and folk museums, as points of pride for local people, and as tangible structures reflecting Japanese history and heritage. As castles are associated with the martial valor of past warriors, there are often monuments near castle structures or in their parks dedicated to either samurai or soldiers of the Imperial Army who died in war, such as the monument to the 18th Infantry Regiment near the ruins of Yoshida Castle (Toyohashi, Aichi). Castle grounds are often developed into parks for the benefit of the public, and planted with cherry blossom trees, plum blossom trees, and other flowering plants. Hirosaki Castle in Aomori Prefecture and Matsumae Castle in Hokkaido are both famous in their respective regions for their cherry blossom trees. The efforts of dedicated groups, as well as various agencies of the government has been to keep castles as relevant and visible in the lives of the Japanese people, to showcase them to visitors, and thus prevent the neglect of national heritage.
Architecture and defenses
Japanese castles were built in a variety of environments, but all were constructed within variations of a fairly well-defined architectural scheme. Yamajiro (山城), or "mountain castles" were the most common, and provided the best natural defenses. However, castles built on flat plains (平城, hirajiro) and those built on lowlands hills (平山城, hirayamajiro) were not uncommon, and a few very isolated castles were even built on small natural or artificial islands in lakes or the sea, or along the shore. The science of building and fortifying castles was known as chikujō-jutsu (築城術).
Walls and foundations
Japanese castles were almost always built atop a hill or mound, and often an artificial mound would be created for this purpose. This not only aided greatly in the defense of the castle, but also allowed it a greater view over the surrounding land, and made the castle look more impressive and intimidating. The use of stone, and the development of the architectural style of the castle, was a natural step up from the wooden stockades of earlier centuries. The hills gave Japanese castles sloping walls, which many argue helped (incidentally) to defend them from Japan's frequent earthquakes.
Techniques were invented to keep attackers off the walls and to stop them from climbing the castle, including pots of hot sand, gun emplacements, and arrow slits from which defenders could fire at attackers while still enjoying nearly full cover. Spaces in the walls for firing from were called sama; arrow slits were called yasama, gun emplacements tepposama and the rarer, later spaces for cannon were known as taihosama. In Japanese castles, the walls' timbers would be left sticking inwards, and planks would be placed over them to provide a surface for archers or gunners to stand on. Other tactics to hinder attackers' approaches to the walls included bamboo spikes planted into the ground at a diagonal, or the use of felled trees, their branches facing outwards and presenting an obstacle to an approaching army. Many castles also had trapdoors built into their towers, and some even suspended logs from ropes, to drop on attackers.
Japanese castles featured massive stone walls and large moats. However, walls were restricted to the castle compound; they were never extended around a jōkamachi (castle town), and only very rarely were built along borders. This comes from Japan's long history of not fearing invasion. Tile-roofed buildings, constructed from plaster over skeletons of wooden beams, lay within the walls, and in later castles, some of these structures would be placed atop smaller stone-covered mounds. Sometimes a small portion of a building would be constructed of stone, providing a space to store and contain gunpowder.
Though the area inside the walls could be quite large, it did not encompass fields or peasants' homes, and the vast majority of commoners lived outside the castle walls. Samurai lived almost exclusively within the compound, those of higher rank living closer to the daimyō's central keep. In some larger castles, such as Himeji, a secondary inner moat was constructed between this more central area of residences and the outer section where lower-ranking samurai kept their residences. Only a very few commoners, those directly in the employ and service of the daimyō or his retainers, lived within the walls, and they were often designated portions of the compound to live in, according to their occupation, for purposes of administrative efficiency.
The primary method of defense lay in the arrangement of the baileys, called maru (丸) or kuruwa (曲輪). Maru, meaning 'round' or 'circle' in most contexts, here refers to sections of the castle, separated by courtyards. Some castles were arranged in concentric circles, each maru lying within the last, while others lay their maru in a row; most used some combination of these two layouts. Since most Japanese castles were built atop a mountain or hill, the topography of the location determined the layout of the maru.
The most central bailey, containing the keep, was called honmaru (本丸), and the second and third were called ni-no-maru (二の丸) and san-no-maru (三の丸) respectively. These areas contained the main tower and residence of the daimyō, the storerooms (kura 蔵 or 倉), and the living quarters of the garrison. Larger castles would have additional encircling sections, called soto-guruwa or sōguruwa. While maru (丸) most literally translates simply to "round" or "circle", kuruwa denotes an area enclosed by earthworks or other walls, and was a term also used to denote the enclosed red-light districts such as the Yoshiwara during the Edo period. As it relates to castles, most castles had three maru, main baileys, which could be called kuruwa; additional areas beyond this would be called sotoguruwa (外廓), or "kuruwa that are outside". At many castles still standing today in Japan, only the honmaru remains.
A complex system of a great many gates and courtyards leading up to the central keep serves as one of the key defensive elements. This was very carefully arranged to impede an invading army and to allow fallen outer portions of the compound to be regained with relative ease by the garrisons of the inner portion. Since sieges rarely involved the wholesale destruction of walls, castle designers and defenders could anticipate the ways in which an invading army would move through the compound, from one gate to another. As an invading army passed through the outer rings of the Himeji compound, it would find itself directly under windows from which rocks, hot sand, or other things could be dropped, and also in a position that made them easy shots for archers in the castle's towers. Gates were often placed at tight corners, forcing a bottleneck effect upon the invading force, or even simply at right angles within a square courtyard. Passageways would often lead to blind alleys, and the layout would often prevent visitors (or invaders) from being able to see ahead to where different passages might lead. All in all, these measures made it impossible to enter a castle and travel straight to the keep. Invading armies would be forced to travel around and around the complex, more or less in a spiral, gradually approaching the center, all while the defenders prepared for battle, and rained down arrows and worse upon the attackers.
Castles were rarely forcibly invaded, however. It was considered more honorable, and more appropriate, for a defender's army to sally forth from the castle to confront his attackers. When this did not happen, sieges were most often performed not with siege weapons or forced entry, but by surrounding the enemy castle and denying food, water, or other supplies to the fortress. As this tactic could often take months or even years to see results, the besieging army sometimes even built their own castle or fortress nearby. This being the case, the castle was less a defensive fortress than a symbol of defensive capacity with which to impress or discourage the enemy. It also served as the lord's residence, a center of authority and governance, and in various ways a similar function to military barracks.
The castle keep, usually three to five stories tall, is known as the tenshukaku (天守閣), and may be linked to a number of smaller buildings of two or three stories. Some castles, notably Azuchi, had keeps of as many as seven stories. The tallest and most elaborate building in the complex, and often also the largest. The number of stories and building layout as perceived from outside the keep rarely corresponds to the internal layout; for example, what appeared to be the third story from outside may have in fact been the fourth. This must have helped to confuse attackers, preventing them from knowing which story or which window to attack, and likely disorienting the attacker somewhat once he made his way in through a window.
The least militarily equipped of the castle buildings, the keep was defended by the walls and towers, and its ornamental role was never ignored; few buildings in Japan, least of all castle keeps, were ever built with attention to function purely over artistic and architectural form. Keeps were meant to be impressive not only in their size and in implying military might, but also in their beauty and the implication of a daimyō's wealth. Though obviously well within the general sphere of Japanese architecture, much of the aesthetics and design of the castle was quite distinct from styles or influences seen in Shintō shrines, Buddhist temples, or Japanese homes. The intricate gables and windows are a fine example of this.
However, the keep was not the primary residence of the lord; there were separate palace buildings, known as goten (御殿) to serve that purpose. Authentic surviving goten are even rarer than authentic surviving tenshukaku. A famous example on an authentic goten is the Ninomaru Goten of Nijo Castle in Kyoto, which served as the Shogun's residence whenever he was visiting Kyoto. It was built with "nightingale floors" that were deliberately designed to squeak when somebody walked on them so the Shogun and his retainers could be warned of any potential assassins.
Palisades lined the top of the castle's walls, and patches of trees, usually pines, symbolic of eternity or immortality, were planted along them. These served the dual purpose of adding natural beautiful scenery to a daimyō's home, representing part of his garden, and also obscuring the insides of the castle compound from spies or scouts.
A variety of towers or turrets, called yagura (櫓), placed at the corners of the walls, over the gates, or in other positions, served a number of purposes. Though some were used for the obvious defensive purposes, and as watchtowers, others served as water towers or for moon-viewing. As the residences of wealthy and powerful lords, towers for moon-viewing, balconies for taking in the scenery, tea rooms and gardens proliferated. These were by no means solely martial structures, but many elements served dual purposes. Gardens and orchards, for example, though primarily simply for the purpose of adding beauty and a degree of luxuriousness to the lord's residence, could also provide water and fruit in case of supplies running down due to siege, as well as wood for a variety of purposes.
It is estimated that once there were 5,00 castles in Japan. Today there are more than 100 castles remaining, or partially extant, but most are modern reconstructions. Because of bombings in World War II, fires, edicts to tear down castles, etc., only 12 of Japan's castles are considered to be originals. These have keeps or donjons (天守閣 tenshukaku) that date back to the days when they were still used. Four of them are on the island of Shikoku, two just north in the Chugoku region, two in Kansai, three in the Chubu region, and one in the northern Tohoku region. There are no original castles in Kyushu, Kanto, Hokkaido, or Okinawa.
The original castles are:
- 1 Uwajima Castle (宇和島城 Uwajima-jō) — a small and modest castle, comparative to others; its Ōte Gate was burnt to the ground by American bombing during World War II
- 2 Matsuyama Castle (松山城 Matsuyama-jō) — this sprawling fortress is one of three multi-wing, flat hilltop castles remaining; it was constructed by the feudal lord Katō Yoshiaki from 1602 to 1627; four of its eight strategic gates are designated national cultural treasures
- 3 Kochi Castle (高知城 Kōchi-jō) — one of the few original white castles in Japan, with spectacular views from the castle; it is the only castle in Japan to retain both its original tenshukaku (keep), and its goten (palace); it is also the only castle to have all the original buildings in the innermost ring of defense still standing
- 4 Marugame Castle (丸亀城 Marugame-jō) — it stands on a man-made hill which is over 50 m high, making it the largest castle mount in Japan; most of what stands is the result of a reconstruction completed in 1644
- 5 Matsue Castle (松江城 Matsue-jō) — nicknamed the "black castle" or "plover castle"; it stands on the shores of Shinji Lake, and is one of Japan's "Three Great Lake Castles"; completed in 1611
- 6 Bitchu Matsuyama Castle (備中松山城 Bitchū-Matsuyama-jō) — the only original mountain castle in the nation, built atop Mount Gagyu, it has the highest elevation at 430 m above sea level; it has gained fame as a "Castle in the Sky" when viewed from afar surrounded by clouds but it is one of the least visited of the original castles
- 7 Himeji Castle (姫路城 Himeji-jō) — called the "White Egret Castle" because of its bright white exterior and its supposed resemblance to a bird taking flight, it is generally considered the most beautiful of Japan's castles; it is virtually the last castle in Japan that still manages to tower over the surrounding skyscrapers and office buildings; a network of 83 rooms with advanced defensive systems from the feudal period. The first Japanese castle to be recognized as a UNESCO World Heritage Site in 1993.
- 8 Hikone Castle (彦根城 Hikone-jō) — tracing its origin to 1603, the castle tower is an official National Treasure and a number of the turrets have been classified as Important Cultural Properties; even the sound of the bell every three hours is preserved as a nationally important soundscape
- 9 Inuyama Castle (犬山城 Inuyama-jō) — the only privately owned castle in Japan and one of the nicest original examples of feudal Japanese fortifications; it is often claimed as the oldest castle in Japan as its original construction was completed in 1440, although the towers were completed in 1537
- 10 Maruoka Castle (丸岡城 Maruoka-jō) — the oldest castle keep (donjon) in Japan; built in 1576, it also claims to be the oldest in the country; it is called the "Mist Castle" because of the legend that whenever an enemy approaches the castle, a thick mist appears and hides it
- 11 Matsumoto Castle (松山城 Matsuyama-jō) — also known as the "Crow Castle" because its black walls and roofs looked like spreading wings.; it was the seat of the Matsumoto domain; it is a flatland castle because it is not built on a hilltop or amid rivers, but on a plain; much of the castle was completed by 1593–94
- 12 Hirosaki Castle (弘前城 Hirosaki-jō) — completed in 1611 for the Tsugaru Clan; 49-hectare grounds include three concentric moats and earthen fortifications that surround the remains of the inner castle area: five castle gates, three corner keeps and a castle tower; the surrounding Hirosaki Park is one of Japan's most famous cherry blossom spots, with 2600 trees
Original palace buildings
Only four castles in Japan still have their original lord's residence (御殿 goten) standing. One of them is the aforementioned Kochi Castle. The other three, whose main keep has not survived are:
- 1 Nijō Castle (二条城 Nijō-jō) — completed in 1679, this was the Kyoto residence of the Tokugawa shoguns whenever they were visiting the emperor. The Ninomaru Goten (二の丸御殿) is the original dating back to 1679, and is known for the intricate paintings on its walls and doors, as well as its "nightingale floors", which were designed to squeak when walked on to warn the lord and his retainers of any potential assassins. The main keep burnt down after bring struck by lightning in 1750, while the original Honmaru Goten (本丸御殿) burnt down in a citywide fire in 1788. The current Honmaru Goten was originally built as a prince's residence on the grounds of Kyoto Imperial Palace and moved here in 1893, though its interior is not open to the public. The enthronement banquet of Emperor Showa was held in the Honmaru Goten in 1928. Part of the Historic Monuments of Ancient Kyoto UNESCO World Heritage Site.
- 2 Kawagoe Castle (川越城 Kawagoe-jō) — completed in 1457, it was originally built by the Ōta clan on the orders of the Hōjō clan, and passed between the control of the Hōjō and Uesugi clans multiple times during the Warring States Period. Much of the buildings were destroyed in a fire in 1846, and rebuilt in 1848. Most of the buildings were demolished in 1870 following the Meiji Restoration in 1868, and only one turret and part of the Honmaru Goten survive.
- 3 Kakegawa Castle (掛川城 Kakegawa-jō) — originally completed between 1469 and 1487 for Asahina Yasuhiro, a retainer of the warlord Imagawa Yoshitada. It was subsequently torn down and rebuilt for Yamauchi Kazutoyo, a retainer of the famous warlord Toyotomi Hideyoshi, in 1590. Most of the restructures were destroyed by an earthquake in 1854, but subsequently rebuilt by 1861, with the exception of the main keep, though most of them would subsequently fall into ruin in the 20th century. The current Ninomaru Goten dates back to the 1861 reconstruction, while the main keep was reconstructed using traditional methods in 1994, making it the first time in the post World War II era that castle has been reconstructed in wood.
Japan has many reconstructed castles, many of which receive more visitors than the originals. A reconstructed castle means that the donjon was rebuilt in modern times, but many of these still have other original structures within the castle grounds. For example, three of the turrets of 1 Nagoya Castle are authentic.
Reconstructions still offer a glimpse into the past and many, like 2 Osaka Castle are also museums housing important artifacts. 3 Kumamoto Castle is considered to be among the best reconstructions, because most of the structures have been reconstructed instead of just the donjon. The only reconstructed castle in Hokkaido is 4 Matsumae Castle. The Sougamae of Odawara Castle is a long distance surrounding the entire castle town with about 9 km of empty hill and ground so that it remains in the city. 5 Kokura Castle was fully restored in 1990. On one floor inside the castle there is a display of scale models of Japan's castles made out of toothpicks. 6 Sumoto Castle (洲本城 Sumoto-jō) is a ruined castle and keep, reconstructed in concrete in 1928.
Okinawa's 7 Shuri Castle is unique among Japan's castles, because it is not a Japanese castle; it was the royal palace of the Ryukyuan Kingdom and built in a distinctive Ryukyuan architectural style, with a much stronger Chinese influence than Japanese-style castles. Unfortunately, the reconstructed main buildings were burnt down in a disastrous fire in 2019, and rebuilding is expected to take many years.
Ruins typically feature only the castle walls or parts of the original layout are visible. Although they lack the structures of reconstructed castles, ruins often feel more authentic without the concrete reconstructions that sometimes feel too commercial and touristy.
Many ruins maintain historical significance, such as 1 Tsuyama Castle, which was so large and impressive, it was considered to be the best in the nation. Today, the castle walls are all that remain but the area is filled with thousands of cherry blossoms. This is common among many ruins, as well as reconstructions.