The Nanbokucho-Seijun-ron (南北朝正閏論)

The Nanbokucho-Seijun-ron is a debate on which of the Imperial Courts, Southern or Northern, was the legitimate dynasty during the Nanbokucho period in Japan ("jun" is the same as "uruu" and means "not legitimate but also not fake").

Summary
Nanbokucho-Seijun-ron before the modern era
Since the start of the modern era, the Nanbokucho-Seijun-ron debate over which of the Imperial Courts, Southern or Northern, was legitimate has continued. The contention of the proponents are generally classified into the Nancho (Southern Court) legitimacy theory, the Hokucho (Northern Court) legitimacy theory, the both line opposition theory, and the both line concurrent theory. To indicate the legitimacy of the Nitta clan, which was considered as the ancestors of the Tokugawa clan, Mitsukuni TOKUGAWA claimed in "Dainihonshi" (Great Japanese History) that the Nancho was the legitimate line. In the same way, Sanyo RAI, who supported the Nancho legitimacy theory, claimed that since Emperor Gokomatsu (Northern Court (Japan)) became the legitimate Emperor because Emperor Gokameyama (Southern Court) abdicated in favor of a more virtuous successor, the Imperial succession of the Northern Dynasty should not be legitimatized because there is a problem with the legitimacy of emperors after Emperor Gokomatsu (however, the historical fact is that no ceremony for abdication by an emperor in favor of a more virtuous successor was carried out, only a ceremony to return the sacred treasures). On the other hand, most of the court nobles at that time were descended from court nobles of the Northern Court (many families divided into Southern and Northern based on the family head), and strongly supported the Northern Court legitimacy theory, together with many aristocratic historians such as Norimitsu YANAGIHARA, and the Imperial Line also considered the Northern Court as legitimate because it was directly connected to the current imperial line, so rituals were also conducted following those policies.

The Nanbokucho-Seijun-ron problem
The academic field of history during the Meiji period conducted evidence-based research comparing the 'Taiheiki' with other documents such as historical books and diaries, and based on this, the 1903 and 1909 revisions of national textbooks for elementary schools depicted both the Southern and the Northern Court as being concurrent. However, this became problematic around 1910 when the textbooks for teachers was revised, and this movement was further fueled by the "Kotoku Incident," which is said to have been caused by socialists such as Shusui KOTOKU and others.

In the editorial of Yomiuri Shinbun issued January 19, 1911, the following idea was proposed: 'If both dynasties are allowed to oppose each other, it is clear that the nation is divided and this is the fault of the government. How can we allow this to be overlooked as suggested by the Education Ministry, because it was just a temporary anomaly?'; 'In Imperial Japan, the true way of determining character is not by knowledge or good deeds but by national emotions, in other words, the cause. In these days of individualism, where even nihilists are appearing, this is a matter of great urgency and importance,' which led to a political debate in the Imperial Diet about whether the Southern or the Northern Court was legitimate.

Regarding this problem, the opposition party, Rikken Kokumin-to Party (Constitutional National Party) and the Dainipponkokutai advocacy group both accused the Katsura Cabinet of the second term at that time. Pressured by the opposition and public opinion, at the Imperial Diet meeting on February 4, 1911, the government officially declared the Southern Court legitimate. Furthermore, the textbooks were revised and the person responsible for writing the textbooks, Sadakichi KIDA, was suspended from his job. In the end, based on the description in "Dainihonshi" (Great Japanese History) as evidence, the Emperor Meiji decided that the Southern Court was the legitimate line because it owned the Three Sacred Treasures (however, the current academic theory has basically established that the three Northern Court emperors, Emperors Kogon, Komyo and Suko, had owned the Three Sacred Treasures, so the assumption that all of the emperors in the Northern Court were 'not legitimate' because they did not own the sacred treasures is incorrect. The Emperor Meiji is said to have ordered to have the ceremonies for the five emperors of the Northern Court to be continued as before) and the Nanbokucho was to be called 'Yoshino-cho period' because the Southern Court was located in Yoshino (Nara Prefecture). Even then, some academics such as Yoshinari TANAKA have argued against using 'Yoshino-cho' (Nanbokucho-Seijun problem).

Afterwards, the view on imperial history before the war mainly consisted of ideological interpretation, such as declaring Takauji ASHIKAGA a villain for rebelling against the Emperor and Masashige KUSUNOKI and Yoshisada NITTA loyalists.

Debate on the Nanbokucho Period after World War II

The Southern Court is still considered to be legitimate after World War II, but the term 'Nanbokucho period' entered the mainstream again based on the actual situation of history. Also, with changes in values and progress in medieval history research, new views regarding the Nanbokucho period such as re-evaluating the achievements of Takauji ASHIKAGA, researching aspects of Masanori KUSUNOKI as an 'Akuto' (rebel), and establishing that Emperor Godaigo's Kenmu Restoration was influenced by Sung-period neo-Cunfucianism and was revolutionary because he aimed for a dictatorship, like a Chinese emperor, have come forth.

Yoshihiko AMINO focused on people with occupations other than farmers and suggested that the Nanbokucho period was a transitional time in Japanese history. Additionally, after the Pacific War, there were appearances of self-claimed emperors such as Hiromichi KUMAZAWA, who claimed that he was a descendant of the Southern Court and therefore the legitimate heir to the throne. However, in terms of bloodlines, the Jimyoin line, rather than the Daikakuji line, is the direct line of descent, and within the Jimyoin line, the Fushiminomiya family is considered the direct line, making the current Imperial family's blood the most noble.