Bansei-Ikkei (Unbroken Imperial line) (万世一系)

"Bansei-Ikkei" literally means one family line through all ages. In many cases, this expression represents the Imperial family or the Imperial system.


The following is Hirobumi ITO's definition of the unbroken Imperial line as the unbroken rules of Imperial succession.

Only direct descendants of emperors can succeed to the throne.

Only male descendants of emperors can succeed to the throne.

Only descendants of the unbroken Imperial family can succeed to the throne.

Japanese mythology that supports the Japanese Imperial system

Emperors' reign of Japan was based on the following legend:
Amaterasu Omikami (the Sun Goddess) gave an oracle that Ninigi-no Mikoto and his descendants should rule Ashihara no nakatsukuni (another word for the country or the location of Japan) forever, and the great-grandchild of Ninigi-no Mikoto, Iwaremiko ascended to the throne as 'Emperor Jinmu.'

According to the "Kojiki" (the Record of Ancient Matters), Amaterasu Omikami said to her grandchild, Ninigi-no Mikoto: 'Ashihara no nakatsukuni is a country which you should rule.'
There were the following sentences in the "Nihonshoki" (the Chronicles of Japan).
My descendants should be the king of Ashihara no chiihoaki mizuho no kuni (another name of Ashihara no nakatsukuni).'
So, my descendants, you should go there and rule.'
Get going.'
The Imperial family will flourish forever as well as heaven and earth.'

This article provided the historical and legal basis for the Emperors' eternal reign of Japan. The article of the Nihon Shoki was clearly rewritten in the Article 1 of the Constitution of the Empire of Japan. The article of the Nihon Shoki created the historical view that from the first Emperor Jinmu to the current Emperor, the Imperial family was never broken and had consistently ruled Japan. Therefore, the unbroken Imperial line is essential for the Japanese Imperial system.

Beginnings of the theory of 'unbroken Imperial line'

The insistence that 'Japanese dynasty is fundamentally different from those of other countries because rulers' family line has never changed in Japan' has been existing as long as the Japanese dynasty has. Japanese people have been proud of this insistence for more than 10 centuries, meanwhile they also have been questioning the veracity of this insistence.

OTOMO no Yakamochi (Around 718 - 785) was one of the greatest poets during the Nara period, who compiled the "Manyoshu"(the oldest anthology of tanka).
OTOMO no Yakamochi wrote the following waka (Japanese poetry) to express his admiration for Emperor Shomu whom he was serving for:
(The following modern translation is based on the English translation by The Japan Society for the Promotion of Science.)

The Imperial family line is unbroken, and their descendants have ruled many provinces for generations.

They have ruled this country which has various deep mountains and many large rivers, and has been given countless tributes and eternally produce valuable products.

This poem mentioned that the Imperial family had lasted long, but it didn't mention how long the family existed.

According to the "Nihonshoki", the starting point of the Japanese dynasty was the first day of the first month in 660 BC when Emperor Jinmu founded the Japanese empire. Prince Shotoku (574 - 622) was the first person to formulate this theory. He aimed to prove that the emperors' dynasty had lasted since ancient times. Japan was actually founded about 1,000 years after the legendary foundation day, but still Japanese people accepted the day written on the Nihonshoki as the actual foundation day of Japan. This is often thought to be the reason why Japan's national structure (political structure) has never changed.

It was also believed that the Imperial family tree, which started from Emperor Jimnu, actually succeeded the family tree from Japanese gods. Therefore, the Japanese Imperial family line was thought to be unbroken and would last forever.

Reaction in China to the theory of the unbroken Imperial line

The insistence that the Japanese Imperial family had lasted since ancient times was made in order to earn admiration not only of Japanese people but also of the Chinese. Japan thought they could give a strong impression to China by the theory of the unbroken Imperial line, because China had a longer history than Japan as a country, but none of their dynasties lasted longer than that of Japan. Given some reactions from China, it would appear thatthey took notice of Japan's insistence and paid respect to Japan on this matter.

The "Shintojo" is a history book about the Tang Dynasty, but it also includes a brief history of Japan. It has a list of 33 Japanese rulers thought to have existed during the ages of gods. It also has an article about the "Nihonshoki" and the names of 58 human Japanese emperors (Emperor Jinmu to Emperor Koko) written on it.

Youoku was one of editors of the "Shintojo". He recorded the information that the Japanese scholar monk, Chonen (938 - 1016) gave to the Chinese Emperor.
Chonen said as follows:
"In Japan, only one Imperial family has ruled the country for 64 generations." "Posts of government officials who handle public administration and military affairs are succeeded by heredity." "Current Japanese Emperor is Emperor Enyu." According to the Kotofu (Imperial family record) recorded since Emperor Jinmu, Emperor Enyu was indeed the 64th emperor, and this fact matched Youoku's information.

The "Soshi" is a history book about the Song Dynasty.
It has an article called the 'Nihonden' (Story of Japan), and in this article, the Emperor of the Northern Sung Dynasty said as follows:

Not only Chinese but also Japanese were absorbed in comparing durations of Japanese and Chinese dynasties.
This matter was described in the "Jinno Shotoki" (A Chronicle of Gods and Sovereigns) written by Chikafusa KITABATAKE (1293 - 1354) as follows:

Reactions from European countries to the theory of 'the unbroken Imperial line'

Europeans in the 16th and 17th centuries accepted the theory of the unbroken Imperial line and the extraordinary long duration of the Japanese Imperial family. It was Europeans who figured that Japan's foundation year was equivalent to the Christian year 660 BC.

Rodrigo de VIVERO was Spanish and an interim governor of the Philippines.
In the "Don Rodorigo's Record of Japan", he described the Japanese as follows:

Japanese Emperor at the time was Emperor Gomizunoo. According to the Kotofu recorded since Emperor Jinmu, Emperor Gomizunoo was actually the 108th emperor.

Bernardino de Avila GIRON was a Spanish trading merchant.
In 1615, he sent the following report from Japan:

In his record, Japan's foundation year was also 660 BC.

Engelbert KAEMPFER was a German doctor who worked at the Dutch trading post located on Dejima (a fan-shaped artificial island) in the bay of Nagasaki.
He described Japan in the "Nihonshi" (the History of Japan) as follows:

In the "Nihonshi", he listed the names and brief biographies of past Japanese emperors in the same order as they appeared in Japanese books.

The theory of 'the unbroken Imperial line' during the Edo period

During the Edo period, people with reverence for emperors emphasized the long duration and consistency of the Imperial family so as to enhance respect and increase support for emperors.

Soko YAMAGA (1622 - 1685) was an expert of Confucianism and military science. He insisted that the Imperial line before Emperor Jinmu lasted 2 million years during the ages of gods.
He wrote the "Chuchojijitsu" (the True Central Empire) in 1669, and in this book, he said as follows:

However, not all intellectuals during the Edo period supported the insistence. Toshiaki HONDA (1743 - 1820) was an intellectual who studied Western studies.
In 1798, he argued as follows:
The world's oldest country, Egypt has a history of 6,000 years, and China insists that they are 3,800 years old.'
Given that only 1,500 years have passed since the accession of Emperor Jinmu, Japan's history is much shorter than those of them.'
Donald KEENE noted the idea that Japan was 1,500 years old amazingly matched the theory of modern scholars that Japan was founded in the end of the third century.

The theory of 'the unbroken Imperial line' during the Meiji period

During the Meiji period, most intellectuals accepted the dogma of the consistency of the Imperial family. Yukichi FUKUZAWA (1835 - 1901) believed the consistency of the Imperial family was the essence for promoting modernization.
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Japanese people was not enforced to believe the dogma of the foundation of Japan. Inazo NITOBE (1862 - 1933) was a Christian educator. When he was the Secretary General of the League of Nations, he clearly mentioned in his public appearance abroad that he doubted the foundation year of Japan.
He attended the meeting of the Japan-Sweden Society held in the capital of Sweden, Stockholm, and in his speech, he said as follows:

The general idea of the unbroken Imperial line during the prewar period.

The theory of the unbroken Imperial line was used as a reason for defying republican institutions and communist revolutions. During this period, the following historical view was formed; and in Japan, the Imperial family and common people were united with each other, and unlike other countries, the Japanese Imperial throne had never been wrested by subjects or been invaded by other countries, and Japanese people always paid respect to emperors. Moreover, Japanese people believed that Japan was a country ruled by the descendants of ancient gods, and eventually, became a world's leading country of high moral. During the prewar period, this belief was integrated with nationalism, and it resulted in forming the historical view of Kokoku Shikan (emperor-centered historiography which is based on state Shinto). Especially during the times from the Meiji Restoration to wartime, the Japanese government officially emphasized this historical view and stated this in the Article 1 of the Constitution of the Empire of Japan.

The theory of unbroken Imperial line during the postwar period

"There were historians during the postwar period who strongly criticized the government for wrongfully using the Imperial family's long duration to promote nationalism during the prewar period, and these historians made light of such a long duration of the Japanese emperor system and the Imperial family." "But still they had to admit the Japanese Imperial family was the oldest sovereign family in the world." The above is the findings of the study after the war.

The theory of the unbroken Imperial line was no longer official during the postwar period, but it was still often used in discussions and speeches at official occasions.
In August, 1977, Emperor Showa made the following speech during the press conference held at the Imperial villa in Nasu:

In the Constitution of Japan, ancestors of the Imperial family and its long duration are not stated at all. However, a legal status of the Imperial family was approved on the basis that the Imperial throne should be succeeded by heredity. During the postwar period, the idea of 'Kigensetsu' (the day commemorating the ascension to the throne of the first Emperor Jimmu) was extinct, but on February 11, 1966 (the same day as Kigensetsu) was approved as the 'National Foundation Day'.

In 1990, Akihito succeeded to the throne. When he succeeded to the throne,the 'Daijo-sai festival' (the festival which held to emphasize the relationship among the emperor, Imperial ancestors and ancient gods) was held. In 1999, "Kimigayo", the song for celebrating the long Imperial lineage was legally recognized as the national anthem by the Law Regarding the National Flag and National Anthem.

The Constitution of the Empire of Japan

In 1889, the Constitution of the Empire of Japan was enacted as the constitution of the modern state. This constitution emphasized that the consistency of the Imperial family was evidence for orthodoxy.
In the "Imperial instruction (preamble) of the Constitution of the Empire of Japan", there is the following sentence:

Thanks to the great virtue of our ancestors, the Imperial throne was succeeded by only one unbroken family, and now I succeeded to the throne….

So, the sentence: "the Empire of Japan is ruled by emperors from the unbroken Imperial family" was stated in the Article 1 of the Constitution. It was the first case that such a poetic sentence mentioned above was used in a modern political document.
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The phrase was often used for official announcements of schools and barracks.

Kimigayo (Japan's national anthem)

In 1880, Kimigayo was adopted as Japan's national anthem. The lyrics for Kimigayo was first appeared in the "Kokin Wakashu" (the anthology of poetry edited in the 10th century) as an poem. Basil Hall Chamberlain translated the lyrics for Kimigayo. The following are the lyrics in Japanese and Chamberlain's translation.

The theme of "Kimigayo" is also for the eternity of the Imperial family. The world's shortest national anthem represents the world's longest dynasty.

Today's government's official view about Kimigayo is as follows:
"Accoding to the Constitution of Japan, "Kimi" indicates the Emperor, who is the symbol of the State and of the unity of the people, and whose position is derived from the consensus-based will of Japanese citizens, with whom sovereign power resides." "Yo" of Kimigayo originally represented only times or eras, but now, in addition to that, it also represents "the State".
"Kimigayo" indicates our State, Japan, which has the Emperor enthroned as the symbol of the State and of the unity of the people by the consensus-based will of Japanese citizens"
"And it is reasonable to take the lyrics of Kimigayo to mean the wish as for the lasting prosperity and the peace of such a country as ours."

Kokutai no hongi

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The following is an article about "the unbroken Imperial line" cited from Kokutai no Hongi.

Other theories of the unbroken Imperial line.

I am the Emperor who was given the grace of gods and a descendant of the unbroken Imperial family, and I hope that my dearest Japanese people can be blessed with the grace of my ancestors.

The Japanese Imperial throne should be succeeded only by male descendants of the unbroken Imperial family (the Article 1 of the Former Imperial House Act).

I am the Emperor who was given the grace of gods and a descendant of the unbroken Imperial family, and I declare to the Japanese people who have a clear loyalty and bravery (the declaration of war to USA and England).

The phrase "the unbroken Imperial line" was sometimes used as a modifier of "the Emperor" in Imperial Rescripts and diplomatic documents.

The origin of the Imperial family

Today, emperors from Emperor Jinmu to Emperor Chuai are presumed to be legendary. Editors of the"Kojiki" and the "Nihonshoki" tried to date the ages of these emperors using the most advanced technology at the time so as to justify the orthodoxy of their emperor, but many modern scholars doubt their dating. Therefore, the editors could not date all ages of such legendary emperors properly, and it caused some contradictions.

There is a possibility that ancient Japan was unified according to precedents of Korea and China. Naoki EGAMI published his opinion that equestrian people moved to Japan in ancient times, and they established the Japanese dynasty which lasts until today. According to a history book of China, the five kings of Wa sent tribute to China.

There is another theory that the 26th Emperor Keitai founded a different family line (this theory is based on the "Nihonshoki" but this book emphasized the unbroken Imperial line).

Given that many evidences are found in official chronicles, it is said that until the 6th century, Japanese dynasties were changed so often, or that many dynasties existed at the same time and ruled different areas respectively. However, no records remain to show the changes of dynasties after the 6th century. Given that the current Japanese dynasty has a history of at least 1,500 years.

Monarch families which existed more than 1,500 years ago in the world are all extinct today. The fact that the Imperial family do not have a family name is thought to be evidence that they have lasted since ancient times. Because the current Imperial family is the only one that Japanese people can find its name in the history of Japan.

Doubts and disputes

The theory of the unbroken Imperial line was often questioned and it grew into considerable disputes.

Disputes during the prewar period

In 1911, an issue of government-designated textbooks and an argument on the legitimacy of either Northern or Southern Dynasty emerged. The term "the period of the Northern and Southern Courts" was used in school history textbooks. This issue of textbooks triggered the argument on the legitimacy of either the Northern or the Southern Dynasty in the Imperial Diet. After that, the term "Yoshino-cho period" was used for school textbooks. As for the issue of textbooks, in the theory of the unbroken Imperial line, the idea that only one Imperial family could succeed to the throne (more than one Imperial family could not exist) was especially controversial. This is the case that the historical view of the period of the Northern and the Southern Courts, which had been common since the Edo period, was denied during the Meiji period. Wars between members of the Imperial family such as Jinshin War were not described in school textbooks.

Given these disputes, the issue of the Northern and the Southern Courts was an essential factor for studying whether the unbroken Imperial line and the emperor-centered historiography were based on actual history. As studies of the Kojiki and the Nihonshoki advanced, scholars began to doubt the existence of early emperors (Eight Undocumented Sovereigns), and some people released the idea that the Japanese dynasty was changed when the 26th Emperor Keitai succeeded to the throne (according to a current study, Emperor Keitai had no blood relationship with emperors before him). As described above, during both the prewar and the postwar periods, scholars often doubted the validity of the unbroken Imperial line from the historical point of view. But, especially during the prewar period, the idea of lese majesty and the Peace Preservation Law prevented people from discussing the validity of the unbroken Imperial line. Most historians and intellectuals could not insist their opinion that denied the unbroken Imperial line.

Relationship with the national structure

The unbroken Imperial line was thought to be an essential factor to justify the emperor system, so it had a large influence on the issue of national structure. When the issue of the Emperor Organ Theory emerged, oracles became the evidence for the emperors' reign. The "Kokutai no Hongi" also emphasized the orthodoxy of oracles and the unbroken Imperial line in its opening sentence. In a series of transformative movements which shaped the Showa Restoration, activists insisted from the viewpoint that the Emperor was the symbol of the unity of people, Emperor's direct reign of Japan could open a closed society, but 'Wily vassals surrounding the Emperor' caused criticism against it. After that, the issue of the unbroken Imperial line was connected with the issue of the emperor system, and it fueled disputes over them.

The issue of succession to the Imperial throne

After World War II, the Imperial family had princesses such as Imperial Princess Aiko, but no prince was born for about 40 years since the birth of Imperial Prince Akishinonomiya Fumihito and now no one could have the right to succeed to the Imperial throne. It raised the possibility that the Imperial House Act could be modified soon and that a female emperor would appear. As a result of this successor problem, a meeting of intellectuals can be held to discuss the modification of the Imperial House Act so as to enable princesses to succeed to the Imperial Throne. However, many people are still opposed to female emperors for the reason that the theory of the unbroken Imperial line will be breached.

The theory of the unbroken Imperial line in other countries.

The Tongan dynasty is also unbroken and has lasted since mythological ages. The oldest king on record is 'Aho'eitu who existed in the 10th century.