Category Archives: JAPAN

Possible Traces of 8th-Century Imperial Pavilion Found in Japan

Possible Traces of 8th-Century Imperial Pavilion Found in Japan

Postholes and other archaeological remains that are believed to be from a dwelling for the empress at the Japanese imperial family’s official residence have been found in the ancient capital of Kyoto.

The remains appear to have been from the Tokaden pavilion, which served as a dwelling for the empress and female palace attendants, and is also mentioned in Heian literature, including “The Tale of Genji” and “The Pillow Book.” It was part of the emperor’s official residence located in the ancient Japanese capital and administrative centre of Heian-Kyo, as Kyoto was known during the Heian period (794-1185).

The postholes and other remains are thought to be from the time that the capital was moved to Heian-Kyo toward the end of the 8th century. It is the first time that remains from a building that was evidently part of the Heian-Kyo imperial residence have been discovered.

Possible Traces of 8th-Century Imperial Pavilion Found in Japan
The Mainichi Postholes and stone arrangements that served as ditches, which are believed to be remains of the Tokaden pavilion of the ancient Heian-Kyo residence of the imperial family, are seen in Kyoto’s Kamigyo Ward, on Aug. 11, 2015, in this image…

The remains were unearthed during excavation work in the city’s Kamigyo Ward, carried out in 2015 by the Kyoto City Archaeological Research Institute, ahead of the construction of a group home, and the institute compiled its findings in a report.

The emperor’s private residence is said to have stretched for about 182 meters from west to east, and some 226 meters from north to south, comprising 17 pavilions, among other structures.

The excavation took place in the northwest part of the residence, which is believed to have housed the Tokaden pavilion as well as the Kokiden pavilion situated to its south.

During the excavation, five holes with diameters of between 1.2 and 1.5 meters were found running from the north to south, with a distance of around 3 to 2.1 meters between each of them.

According to the investigation, the holes were used to bury pillars in the ground without placing foundation stones.

The research institute consulted a document from the Edo period (1603-1867), which detailed the positioning of the palace buildings, and determined that the holes had been located at the southwest section of the Tokaden pavilion, which extended about 12 meters from west to east, and about 27 meters from north to south.

Furthermore, an arrangement of stones forming an L-shaped ditch, which was used to carry off rainwater from the roof, was discovered in the southwest corner of the Tokaden, and a similar ditch was also found in the northern part of the Kokiden pavilion.

A foundation stone was placed between the stone ditches, which may be traces of a corridor that connected the two buildings. The ditches are thought to be remains from the 10th century or later after the original building was rebuilt using the method of placing pillars on foundation stones.

Emperor Kanmu, who established Japan’s capital at Heian-Kyo in 794, was devoted to the culture of the Tang Dynasty in China.

It is accordingly believed that major buildings at the time were constructed by placing pillars on foundation stones, which was a method that was introduced in China.


The investigation at the site indicates that the Japanese traditional method of not using foundation stones was also adopted for Heian-Kyo.

A representative of the research institute commented, “There is great significance in finding remains from a building from the time of the establishment of the ancient capital in Kyoto. This is first-class material.”

The postholes and other archaeological remains that were found have already been backfilled.

Parasite eggs in old toilet came from pork eaten 1,300 years ago

Parasite eggs in old toilet came from pork eaten 1,300 years ago

Nara Prefecture–Denizens of the Asuka Period (592-710) feasted on pork and may have done so routinely, archaeologists deduced from parasite eggs excavated from a toilet structure found in the ruins of the ancient capital of Fujiwarakyo. 

The eggs, which serve as scientific evidence of pork consumption because humans are infected with parasites after eating undercooked pork, are one of the oldest findings in the country, researchers from the Archaeological Institute of Kashihara, Nara Prefecture, reported. 

It is possible that immigrants from the Chinese continent ate pork regularly, they added.

The institute excavated the ruins of Fujiwarakyo, which served as the imperial capital between 694 and 710 in Sakurai, also in the prefecture, in the year ending in March 2019. It found a toilet structure in the northeast of the remains of the Fujiwara no Miya palace, the centerpiece of the capital.

Masaaki Kanehara, a professor of environmental archaeology at Nara University of Education who also serves as a collaborative researcher at the institute, and his wife, Masako, head director of the Cultural Assets Scientific Research Center, a general incorporated association, analyzed soil samples.

According to the researchers, there were five egg shells found in the soil. The eggs were apparently laid by a parasite known as a pork tapeworm, which infects humans when they eat pork.

Although bones of boars or pigs possibly raised by humans had been found when the institute conducted a survey at Fujiwarakyo in the year ending in March 2001, no pork tapeworm eggs were discovered at the time.

Similar parasite eggs had also been found in toilet structures of the ruins of Korokan in Fukuoka, which is referred to as the “ancient guest palace,” and Akita Castle in Akita. Both structures apparently date to the Nara Period (710-784), meaning that the eggs were younger than those found at Fujiwarakyo.

Previously, what appeared to be pig bones were found from an archaeological site dating back to the Yayoi Period (c. 1000 B.C.-250 A.D.). But parasite eggs provide more direct evidence for pork consumption.

Professor Kanehara said that the parasite eggs were excreted by humans after they ate undercooked pork. It is also possible that they ate pork on a routine basis because the eggs were found in the remains of the toilet facility used on a daily basis.

In the late seventh century, just before Fujiwarakyo, believed to be Japan’s first full-scale capital laid out in a grid pattern on the ancient Chinese model, was built, the Baekje and Goguryeo kingdoms in the Korean Peninsula both were conquered. It is thought that many of the emigrants fled to Japan.

The parasite eggs show that people who came from the food cultures of the Chinese continent and Korean Peninsula lived in Fujiwarakyo, the institute said in its report released in the spring.

“(The parasite eggs) are important pieces of information to shed light on a meat-eating culture in the history of eating habits in Japan because many facts about pig breeding and the regular consumption of pork at the time remain unclear,” said Masashi Maruyama, an associate professor of zooarchaeology at Tokai University’s School of Marine Science and Technology who studies the history between humans and animals from the standpoint of archaeology.

“Unlike cows and horses, pigs don’t require pastures. It is quite possible that they were bred inside Fujiwarakyo.”


Various pieces of “circumstantial evidence” indicate that pork had also been consumed even in older times.

Excavated from a Yayoi Period site in Oita was what appeared to be a pig skull. With similar bones also having been unearthed at other Yayoi Period ruins, they are collectively referred to as the “Yayoi pig” to differentiate them from wild boars. It is possible that there were people who raised pigs and ate them.

Meanwhile, the word “ikainotsu” is mentioned in one section in “Nihon Shoki” (The Chronicles of Japan), a book of classical Japanese history compiled in the eighth century, which is dedicated to the period of time when Emperor Nintoku reigned. It suggests that there were people whose jobs were to breed boars.

Another entry shows that the meat from cows, horses, dogs, monkeys and chickens were forbidden from consumption in 675, just before the capital was relocated to Fujiwarakyo. However, there are no direct mentions of pigs and boars. The practice of eating animal meat became increasingly shunned with the spread of Buddhism, which prohibits killing.

However, according to Maruyama, the meat of pigs and boars were eaten in Edo (present-day Tokyo), Osaka, Hakata and Nagasaki’s Dejima island, on which the Dutch trading post was located, in the Edo Period (1603-1867). Animal bones were also excavated from historical sites in each region.

The Tokyo-based Japan Pork Producers Association states on its website that pig and boar breeding became widespread in Japan after techniques were presumably brought into Japan by immigrants from the Chinese continent and Korean Peninsula between 200 and 699.

But it makes it unclear as to exactly when livestock breeding began, citing there are varying opinions.

2,000-Year-Old Scale Weights identified in Japan

2,000-Year-Old Scale Weights identified in Japan

KASUGA, Fukuoka Prefecture–Prehistoric people in Japan apparently used an advanced system of weights and measurements on a decimal basis, excavations at a Yayoi Pottery Culture Period (1000 B.C.-A.D. 250) site here suggest.

2,000-Year-Old Scale Weights identified in Japan
Artefacts newly identified as a decuple weight, right, and a trigintuple weight shown at the Nakoku-no-Oka historical museum in Kasuga, Fukuoka Prefecture, on Sept. 1

Researchers identified what is known as a decuple weight with 10 times the reference unit mass of 11 grams among artefacts unearthed at a series of archaeological sites collectively known as the Sugu group, where many measurement weights have previously been discovered, the Kasuga municipal board of education said.

Board officials said on Sept. 1 that the decuple weight, the first artefact of its kind to be found in Japan, offers valuable insight into Yayoi culture.

The stone, which is cylindrical in shape, weighs 116.3 grams.

Unearthed in 1989 from the Sugu-Okamoto archaeological site, the artefact was recently re-examined by researchers who included Junichi Takesue, a Fukuoka University professor emeritus of archaeology, who identified it as a measurement weight.

The object was likely used with a set of scales, he said.

The archaeologists identified another artefact from the same site as a trigintuple weight, with 30 times the reference unit mass.

Weights with 1, 3, 6, 20 and 30 times the reference unit mass were identified last year among artefacts previously found at the Sugu sites.

Bronze weights measuring approximately 11 grams, which likely follow the same scaling system, have also been unearthed at an archaeological site in southern South Korea.

The Sugu site group is believed to have formed a core part of the early Japanese state of Na, which is mentioned in “Weizhi Worenzhuan,” a section of a Chinese history book dating from the third century.

It is believed a bronzeware workshop was located near the site where the decuple weight was unearthed. Researchers speculated that the weights may have been used to weigh copper and lead used for the mix.

“This latest find shows beyond all doubt that the area here was an advanced zone, a sort of ‘technopolis’ of the Yayoi Pottery Culture Period and that the Yayoi people were using the decimal system,” Takesue said.

The decuple weight was set to be displayed, along with a set of other weights, as part of a special exhibition at the Nakoku-no-Oka (state-of-Na hill) historical museum in Kasuga from late August. However, the museum remains closed due to a COVID-19 state of emergency declared for Fukuoka Prefecture.

In light of this, the museum Sept. 1 began displaying images of the weights on its website. The online exhibition, annotated in Japanese, runs through Sept. 26.

DNA Analysis Identifies Japanese Ancestors

DNA Analysis Identifies Japanese Ancestors

Researchers have rewritten Japanese history after uncovering a third, and a previously unknown, group of ancestors that migrated to Japan around 2,000 years ago, of modern-day Japanese populations.

DNA Analysis Identifies Japanese Ancestors
A buried skeleton from the early Jomon period.

Ancient Japan can be split into three key time periods: the Jomon period (13,000 B.C. to 300 B.C.), a time when a small population of hunter-gatherers who were proficient in pottery lived exclusively on the island; the overlapping Yayoi period (900 B.C. to A.D. 300), when farmers migrated to Japan from East Asia and developed agriculture; and the Kofun period (A.D. 300 to 700) when modern-day Japan began to take shape.

Previous research had suggested the two main genetic origins of modern-day Japanese populations were the original hunter-gatherers who lived during the Jomon period and the farmers who migrated to Japan during the Yayoi period. Now, an analysis of the DNA found in ancient bones has revealed a third genetic origin during the Kofun period, when a group of previously unknown ancestors migrated to Japan, researchers reported in a new study. 

“We are very excited about our findings on the tripartite [three-part] structure of Japanese populations,” lead author Shigeki Nakagome, an assistant professor in the School of Medicine at Trinity College Dublin in Ireland, told Live Science. “We believe that our study clearly demonstrates the power of ancient genomics to uncover new ancestral components that could not be seen only from modern data.”

Uncertain origins

The Jomon hunter-gatherers may have first appeared in Japan as early as 20,000 years ago and maintained a small population of around 1,000 individuals for thousands of years, Nakagome said. There is evidence of people living in Japan as far back as 38,000 years ago, during the Upper Paleolithic, the researchers said in a statement, but little is known about these people.

“A long-standing hypothesis is that they were ancestors of Jomon,” Nakagome said. This means that the Upper Paleolithic people may have transitioned into the Jomon people around 16,000 years ago, he added. 

Another possible explanation is that Jomon people originated in East Asia and crossed the Korea Strait when it became covered in ice during the Last Glacial Maximum — the most recent time during the Last Glacial Period when ice sheets were at their greatest extent — around 28,000 years ago, according to the statement.

“However, whether these hypotheses are true or not remains unknown due to a lack of Paleolithic genomes from Japan,” Nakagome said.

At the start of the Yayoi period, there was an influx of people from China or Korea with experience in agriculture. These people introduced farming to Japan, which led to the development of the first social classes and the concept of land ownership. The Yayoi period transitioned into the Kofun period, during which the first political leaders emerged and a single nation, which later became modern-day Japan, was formed. However, until now, it was unclear if the Kofun transition was the result of the third mass migration or just a natural continuation of the Yayoi period.

“Cultural transitions could have happened without involving genetic changes,” Nakagome said. “Even if cultures look very different between two periods, it does not mean that process involved gene flow.”

Previous research had suggested a third genetic input from immigrants at the time, but until now, nobody had been able to sequence DNA from any Kofun individuals to find out.

Missing link 

In the new study, Nakagome and his team analyzed the genomes of 12 individuals from across Japan. Nine dated to the Jomon period, and three were from the Kofun period, making it “the first study that generated whole-genome sequence data from Kofun individuals,” Nakagome said. 

A skull from the late Jomon period was used in the analysis.

The results revealed that, as predicted by others, a third genetically distinct group of Japanese ancestors migrated to the country during the Kofun period. These ancestors came from East Asia and were most likely Han people from ancient China, Nakagome said.

“Han is genetically close to ancient Chinese people from the Yellow River or West Liao River, as well as modern populations, including the Tujia, She and Miao,” Nakagome said. “We think these immigrants came from somewhere around these regions.”

The team’s findings are not unsurprising to other historians who had suspected that this third group of Japanese ancestors existed.

“Archaeological evidence has long suggested three stages of migration, but the last one has largely been ignored.” Mikael Adolphson, a professor of Japanese history at the University of Cambridge who was not involved with the study, told Live Science. “This new finding confirms what many of us knew, but it is good that we now get evidence also from the medical field.”

The findings also showed that a majority of genes among modern-day Japanese populations originated from East Asia, across the three main periods of genetic mixing. The team’s analysis determined that “approximately 13%, 16% and 71% of Jomon, Northeast and East Asian ancestry, respectively,” Nakagome said. “So, East Asian ancestry is dominant in modern populations.”

However, the study does not shed light on whether the migration of East Asian people contributed to the transition from farming to an imperial state during the Kofun period.

“The Kofun individuals sequenced were not buried in keyhole-shaped mounds [reserved for high-ranking individuals], which implies that they were lower-ranking people,” Nakagome said. “To see if this East Asian ancestry played a key role in the transition, we need to sequence people with a higher rank.”

Nakagome and his team are excited to have helped confirm a new piece of Japan’s history and hope the findings can open the door to further discoveries. It is important to know “where we came from and the unique history of our own ancestors,” he said.

The study was published online on Sept. 17 in the journal Science Advances.

Extensive Hyper-Violence in Japan’s Ancient Yayoi Period Revealed by Researcher

Extensive Hyper-Violence in Japan’s Ancient Yayoi Period Revealed by Researcher

The human capacity for warfare and whether it is an inescapable part of human nature is a hot button issue at the heart of various disciplines like anthropology, archaeology, philosophy, and so on.

Researchers have posited a range of ideas about why humans engage in war, and the running list of various triggers for inter-group violence is long, be it the transition from hunting and gathering to agriculture, the development of weapons, ecological constraints, or population pressures.

Among these, the population pressure hypothesis has become more prominent recently as people globally experience climatic changes and environmental breakdown.

The hypothesis states that population increase can result in resource scarcity, leading to competition and conflict over resources. While there is wide acceptance of this claim, there are very few studies that have quantitatively backed up the origin of inter-group violence due to population pressure based on actual archaeological data.

To correct this gap, Professor Naoko Matsumoto from Okayama University and her team surveyed the skeletal remains and jar coffins, called kamekan, from the Middle Yayoi period (350 BC to AD 25 CE) in northern Kyushu, Japan.

These images from the recent study show evidence of violence in the cut mark on this Yayoi period man just above his right eye socket.

This region has been the focus of inter-group violence investigations because the skeletal remains in the Yayoi period indicate a significant increase in the frequency of violence compared to those living in the preceding Jomon period.

“The inhabitants of the Yayoi period practised subsistence agriculture, in particular wet rice cultivation,” says Professor Matsumoto. “This was introduced by immigrants from the Korean peninsula along with weapons such as stone arrowheads and daggers, resulting in enclosed settlements accompanied by warfare or large-scale inter-group violence. However, those living during the Jomon period were primarily pottery-makers who followed a complex hunter-gatherer lifestyle and had low mortality rates caused by conflict.”

Professor Matsumoto and her team inferred demographic changes using the numbers of well-dated burial jars as a proxy for population size and estimated population pressure from the ratio of population to arable land.

The team calculated the frequency of violence by using percentages of injured individuals identified within the skeletal population, followed by a statistical analysis between population pressure and the frequency of violence.

Analyses of the human skeletal remains excavated at the Middle Yayoi period Doigahama site (near Shimonoseki, Japan; the closest point on Honshu island to Kyushu island) showed that Yayoi people skulls (upper two) were relatively longer and flatter than those of the earlier Jomon people (lower two).

The results of the investigation were published in the Journal of Archaeological Science. The researchers uncovered 47 skeletal remains with trauma, in addition to 51 sites containing burial jars in the Itoshima Plain, 46 in the Sawara Plain, 72 in the Fukuoka Plain, 42 in the Mikuni Hills, 37 in the east Tsukushi Plain, and 50 in the central Tsukushi Plain, encompassing all six study sites.

They found that the highest number of injured individuals and the highest frequency-of-violence levels occurred in the Mikuni Hills, the east Tsukushi Plain, and the Sawara Plain. Interestingly, the Mikuni Hills and the central Tsukushi Plain also showed the highest overall values for population pressure. Overall, statistical analyses supported that population pressure affected the frequency of violence.

However, the peak population did not correlate with the frequency of violence. High levels of population pressure in the Mikuni Hills and the central Tsukushi Plain showed low frequency-of-violence values, while the relatively low population pressures of the east Tsukushi Plain and Sawara Plain were linked to higher frequency-of-violence levels.

Professor Matsumoto reasons there may be other factors that could have indirectly influenced such high levels of violence in the Middle Yayoi period. “I think that the development of a social hierarchy or political organization might also have affected the level of violence.

We have seen stratified burial systems in which certain members of the ruling elite, referred to as ‘kings’ in Japanese archaeology, have tombs with large quantities of prestige goods such as weapons and mirrors,” she says.

“It is worth noting that the frequency of violence tends to be lower in the subregions with such kingly tombs. This suggests that powerful elites might have a role in repressing the frequency of violence.”

The evidence collected by Professor Matsumoto and her team undeniably confirms a positive correlation between population pressure and higher levels of violence and may help devise mechanisms to avoid seemingly never-ending conflicts in motion today.

Further research based on these insights could identify other variables at play in determining the root causes of inter-group violence and actively prevent them.

Eighth-Century Imperial Structure Uncovered in Japan

Eighth-Century Imperial Structure Uncovered in Japan

Archaeologists have excavated one of the largest ruins of a building ever found at the former site of the Heijokyu palace in this ancient capital. The Nara National Research Institute for Cultural Properties announced the findings at the government-designated special historic site on June 30.

It believes the structure was the centrepiece of a residence for emperors and crown princes during the late eighth century.

One expert said the building was likely a residence for female Emperor Koken (718-770).

Eighth-Century Imperial Structure Uncovered in Japan
Remains of a structure unearthed at the former site of the Heijokyu palace in Nara.

Archaeologists began examining a roughly 924-square-meter plot in the northern Toin district in March, according to the institute. Toin is located in the eastern part of the Heijokyu palace, the nerve centre of politics during the Nara Period (710-784).

They unearthed ruins of a rectangular-shaped structure, which spans 27 meters in an east-west direction and 12 meters in a north-south direction. Also found were 50 pits dug in the ground to place pillars into them. The holes are lined up about 3 meters apart.

The building, supported by pillars placed in a grid-like formation, likely served as a living space, according to the institute.

The researchers concluded that the structure stood there between 749 and 770 during the Nara Period, based on the characteristics of a pattern on roof tiles found in the pits.

Part of roof tiles retrieved from the ruins of a building excavated at the former site of the Heijokyu palace in Nara.
Ruins of what appears to be a cooking stove found among the remains of a structure unearthed at the former site of the Heijokyu palace in Nara.

During the building’s roughly 20-year lifespan, Koken ruled from 749 to 758 before abdicating in favour of Emperor Junnin. Koken, known to have favoured a Buddhist monk named Dokyo, again ascended to the throne as Emperor Shotoku from 764 to 770.

Shoku Nihongi,” the imperially commissioned history text on the Nara Period, notes that Emperor Shomu (701-756), father of Koken, resided in Toin when he was crown prince.

The area was later used as a site to build a residence for emperors.

“Koken particularly liked Toin, according to Shoku Nihongi,” said Akihiro Watanabe, a professor of Japanese ancient history at Nara University. “I believe the (discovered) structure was her living space.”

The institute said it plans to post a video of the ruins on its official YouTube channel in late July. 

Remains of a 3000-year-old shark attack victim discovered in Japan

Remains of a 3000-year-old shark attack victim discovered in Japan

Newspapers regularly carry stories of terrifying shark attacks, but in a paper published today, Oxford-led researchers reveal their discovery of a 3,000-year-old victim – attacked by a shark in the Seto Inland Sea of the Japanese archipelago.

The research in the Journal of Archaeological Science: Reports, shows that this body is the earliest direct evidence for a shark attack on a human and an international research team has carefully recreated what happened – using a combination of archaeological science and forensic techniques.

The grim discovery of the victim was made by Oxford researchers, J. Alyssa White and Professor Rick Schulting, while investigating the evidence for violent trauma on the skeletal remains of prehistoric hunter-gatherers at Kyoto University.

They came upon No24, from the previously excavated site of Tsukumo, an adult male riddled with traumatic injuries.

‘We were initially flummoxed by what could have caused at least 790 deep, serrated injuries to this man,’ say the Oxford pair. ‘There were so many injuries and yet he was buried in the community burial ground, the Tsukumo Shell-mound cemetery site.’

They continue, ‘The injuries were mainly confined to the arms, legs, and front of the chest and abdomen. Through a process of elimination, we ruled out human conflict and more commonly-reported animal predators or scavengers.’

Since archaeological cases of shark reports are extremely rare, they turned to forensic shark attack cases for clues and worked with expert George Burgess, Director Emeritus of the Florida Program for Shark Research. And reconstruction of the attack was put together by the international team.

The team concluded that the individual died more than 3,000 years ago, between 1370 to 1010 BC. The distribution of wounds strongly suggest the victim was alive at the time of the attack; his left hand was sheared off, possibly a defence wound.

Individual No 24’s body had been recovered soon after the attack and buried with his people at the cemetery. Excavation records showed he was also missing his right leg and his left leg was placed on top of his body in an inverted position.

According to the pair, ‘Given the injuries, he was clearly the victim of a shark attack.

Remains of a 3000-year-old shark attack victim discovered in Japan

The man may well have been fishing with companions at the time, since he was recovered quickly. And, based on the character and distribution of the tooth marks, the most likely species responsible was either a tiger or white shark.’

Co-author Dr Mark Hudson, a researcher with the Max Planck Institute, says, ‘The Neolithic people of Jomon Japan exploited a range of marine resources…

It’s not clear if Tsukumo 24 was deliberately targeting sharks or if the shark was attracted by blood or bait from other fish. Either way, this find not only provides a new perspective on ancient Japan but is also a rare example of archaeologists being able to reconstruct a dramatic episode in the life of a prehistoric community.’

Original 15th-Century Castle Wall Found in Tokyo

Original 15th-Century Castle Wall Found in Tokyo

The Mainichi reports that a 400-year-old stone wall standing about 13 feet tall has been uncovered at Edo Castle, which was constructed in the mid-fifteenth century A.D. by Ōta Dōkan, a samurai warrior-poet who eventually became a Buddhist monk.

The historic remnants were excavated at the spot where Sannomaru Shozokan (Museum of the Imperial Collections) is undergoing renovation work, in the East Garden of the Imperial Palace, in Tokyo’s Chiyoda Ward.

The stone walls are not thought to have been repaired since they were first built at the beginning of the Edo period (1603-1867). An official at the Chiyoda Ward Government said the finding “allows us to examine stone wall construction techniques at the time.”

Original 15th-Century Castle Wall Found in Tokyo
Stone walls from the Edo Castle, thought to be about 400-years-old, are seen at a construction site in the Imperial Palace in Tokyo’s Chiyoda Ward

According to the ward government, the stone walls were found near the Imperial Palace’s Otemon Gate.

They run about 16 meters north to south and measure about 4 meters high — or about seven steps. It seems they were part of the stone wall for the water-filled moat, and a band-shaped white line for indicating the water flow at the time remains on its surface. It is believed water went up to the stone walls’ fourth to fifth steps.

Researchers assume the whole stone walls were buried by the mid-1600s, based on the loss of its top, the condition of soil on the structure, and drawings from the time.

The field excavation survey was conducted from November to December 2020. Researchers are examining and analyzing the excavated relics and soil and will summarize the results in the future. The stone walls will be covered with soil again afterwards.

Stone walls from the Edo Castle, thought to be about 400-years-old, are seen at a construction site in the Imperial Palace in Tokyo’s Chiyoda Ward

Sannomaru Shozokan is set to greatly expand its storage and exhibition areas and had aimed to open fully to the public in 2025, but the effects of the excavation survey mean a year’s delay is now expected.