The Soga held great political influence at court from the late sixth to the early seventh century, until the main line of the clan fell in the Isshi Incident of 645. That political upheaval reshaped the balance of power in imperial succession and court politics, and became an important turning point in the state formation that followed.
The Soga were deeply involved in the acceptance of Buddhism, in exchange with the Korean peninsula and the Chinese continent, and in the development of political institutions, and they held great influence at court in the early seventh century. In the Isshi Incident of 645, however, the main line of Soga no Emishi and Iruka fell. Afterwards the Fujiwara clan rose through Kamatari's son Fujiwara no Fuhito and his descendants, and in the Heian period came to hold great influence at court through regency politics.
The Isshi Incident was a court coup in 645 CE where Prince Naka no Ōe and Nakatomi no Kamatari assassinated Soga no Iruka inside the imperial court, ending Soga dominance and initiating the Taika Reforms.
By combining the positions of Sesshō and Kampaku with marriage ties to the emperor, the Fujiwara clan gained great influence over court politics in the Heian period. Marrying their daughters to the emperor and raising their sons as heirs built the maternal-kinship ties that became the political foundation of the regent house.
The Soga and Fujiwara clans were two of the most powerful aristocratic families in early Japanese history, each developing different strategies for influencing the imperial court. The Soga exercised extraordinary political influence during the sixth and seventh centuries before their dominance was violently broken in the 645 CE Isshi Incident. The Fujiwara later built a more durable system of court power through marriage alliances, regency, and influence over court office, becoming central to Heian-period politics.
Against the background of exchange with the Korean peninsula and the Chinese continent, the Soga were deeply involved in the acceptance of Buddhism, writing, and institutions, and they supported the political changes of the Yamato royal house.
According to the Nihon Shoki, Emperor Sushun was assassinated in 592 by Yamato no Ayabe no Koma, acting on the intention of Soga no Umako. It is an extremely rare event in ancient Japanese history, in which a subject was involved in the killing of an emperor.
The Nihon Shoki records that Prince Yamashiro no Ōe, son of Prince Shōtoku, was attacked at Ikaruga Palace by the forces of Soga no Iruka and took his own life together with his family.
Father to Bidatsu, Yōmei, Sushun, and Suiko. His reign saw problems surrounding the public transmission of Buddhism and the political and religious conflict between the Soga and clans such as the Mononobe. The deep bonds between the royal line and Soga no Iname's daughters through marriage were also a feature of this era.
Son of Kinmei and father of Prince Oshisaka no Hikohito Ōe, who was the father of the future Emperor Jomei. He and Suiko were half-siblings, and he was also Suiko's husband. His reign saw continuing conflict between the Soga and clans such as the Mononobe over the acceptance of Buddhism.
Son of Bidatsu and father of the future Emperor Jomei. He is considered to have been one of the leading candidates for the throne after the death of Emperor Yōmei, but his dates and later movements are unclear. Traditions also tell that he came under political pressure amid conflict with clans such as the Mononobe, but no assassination can be confirmed.
His place in the succession story is important: Jomei was Bidatsu’s grandson through Oshisaka no Hikohito Ōe.
Son of Kinmei, brother of Suiko, and father of Prince Umayado (later known as Prince Shōtoku). He ascended the throne amid continuing political conflict over the acceptance of Buddhism, and died of illness during his reign.
Another son of Kinmei and brother of Suiko. He became emperor after the defeat of the Mononobe and was later assassinated in 592 by Yamato no Ayabe no Koma at the behest of Soga no Umako. The event has come to symbolize the strained relations between the emperor and powerful clans.
Generally regarded as the first empress of Japan. Her reign is traditionally associated with Prince Umayado (later called Prince Shōtoku), who played a major political role rather than serving as a modern-style regent. In the court of Suiko, embassies were dispatched to Sui, including Ono no Imoko's mission in 607.
Grandson of Bidatsu and husband of Empress Kōgyoku. During his reign Soga no Emishi held great political influence as Minister, and after Emperor Jomei's death the conflict over the succession deepened further.
The Nihon Shoki presents the Soga, especially Emishi and Iruka, in strongly negative terms and portrays their overthrow as part of the restoration of royal authority. Recent scholarship has challenged a simple "Soga tyrants versus imperial loyalists" interpretation, emphasizing the clan's role in Buddhism, continental connections, administrative development, and state formation. How the Soga image in the Nihon Shoki came to play a role in legitimizing the post-645 order of royal power remains a matter of debate.
One of the leading figures who, together with Prince Naka no Ōe, directed the Isshi Incident. He later deepened his political relationship with Prince Naka no Ōe and was granted the Fujiwara surname in 669.
Soga no Iruka is assassinated in the presence of Empress Kōgyoku. According to the Nihon Shoki, Soga no Emishi set fire to his own residence and took his own life, and treasures and state records such as the national annals were lost in the flames.
Prince Arima was executed in 658 on suspicion of treason. It is considered that political conflict over the imperial succession lay behind the event.
Mother of Prince Naka no Ōe and Prince Ōama, and wife of Emperor Jomei. She abdicated after the 645 Isshi Incident and was succeeded by her brother Kōtoku, then resumed the throne as Emperor Saimei in 655. She addressed political challenges at home and abroad, including the situation on the Korean peninsula and military policy toward the northeast and the western provinces.
Moved the court to Naniwa Nagara-Toyosaki Palace (in present-day Osaka City) after the Isshi Incident of 645. His reign is traditionally associated with the Taika reforms and the court's efforts to restructure landholding, taxation, and provincial administration, although the precise dating and implementation of individual reform measures remain debated.
Directed the Isshi Incident of 645 together with Nakatomi no Kamatari and later ascended the throne as Emperor Tenji. He established his court at Ōmi Ōtsu, pursued administrative reforms, and strengthened central institutions. Nakatomi no Kamatari was granted the Fujiwara surname in 669, shortly before his death. In 698 it was determined that the surname would pass only to the descendants of Kamatari's second son, Fujiwara no Fuhito, fixing the main line of the Fujiwara clan in Fuhito's line.
Won the Jinshin War of 672 and ascended in 673. He strengthened royal authority and advanced the centralization of the state, including institutional developments that led toward the formation of the ritsuryō state.
Wife and successor of Tenmu. She continued the centralization of the court, oversaw the completion and occupation of Fujiwara-kyō, and advanced the formation of the ritsuryō state, including the compilation of household registers.
The Nihon Shoki presents the 645 assassination of Soga no Iruka as a decisive act that restored royal authority. Recent historiography also recognizes the event as a violent court coup that removed a powerful political faction and transformed the balance of power. The extent to which Prince Naka no Ōe's actions were a planned seizure of power, a response to Soga dominance, or both remains an important interpretive question.
Second son of Nakatomi no Kamatari and a central figure behind the rise of the Fujiwara family. Fuhito's daughter Miyako was the consort of Emperor Monmu and the mother of the future Emperor Shōmu, while his daughter Kōmyōshi became Shōmu's empress. Fuhito was thus the maternal grandfather of Emperor Shōmu and at the same time the father of his empress — placing the Fujiwara exceptionally close to the imperial line.
Fuhito was also closely involved in the political world surrounding the Taihō Code of 701, although attributing the code's authorship to one individual oversimplifies its compilation.
Nakamaro became the most powerful court aristocrat under Empress Kōken and helped bring Prince Ōi to the throne as Emperor Junnin in 758. He built up power on both the military and administrative fronts, but his relations with the retired Empress Kōken and her intimates deteriorated, leading to Fujiwara no Nakamaro's Rebellion of 764.
When Fujiwara no Nakamaro raised arms against the side of the retired Empress Kōken in 764, the forces of Empress Shōtoku secured the relay bells and the inner seal, and Nakamaro was subdued as a rebel.
Following Nakamaro's defeat, Emperor Junnin was deposed in 764 and banished to Awaji, where he died the following year in 765. The circumstances of his death remain a matter of debate, including in later records.
Grandson of Emperor Tenmu and Empress Jitō, and son of Prince Kusakabe. He succeeded Jitō and reigned during a period in which the institutional development of the ritsuryō state was advancing. His early death in 707 created another succession crisis, leading his mother, Genmei, to ascend the throne.
Monmu was the father of the future Emperor Shōmu, making Genmei his mother and Genshō his aunt.
Mother of Emperor Monmu and grandmother of the future Emperor Shōmu. She succeeded after Monmu's early death, because the future Emperor Shōmu was still an infant. She moved the capital to Heijō-kyō in 710, and her reign oversaw major stages in the consolidation of the early centralized state.
Daughter of Genmei, she ascended the throne after receiving the abdication from her mother. Her reign continued the administrative and cultural consolidation of the Nara court.
Devout Buddhist sovereign who commissioned Tōdai-ji and the Great Buddha. Empress Kōmyō was a daughter of Fujiwara no Fuhito and the first woman of non-imperial birth to become empress. The marriage of Emperor Shōmu and Empress Kōmyō marked a major development in Fujiwara influence at the heart of the imperial court.
Daughter of Emperor Shōmu and Empress Kōmyō. She first reigned as Kōken, abdicated in 758, and returned to the throne as Shōtoku in 764 after the defeat of Fujiwara no Nakamaro. As Dōkyō's political influence grew, an imperial succession problem arose over the oracle of the Usa Shrine, which became the center of intense court controversy.
Moved the capital to Nagaoka-kyō in 784 and then to Heian-kyō in 794, taking distance from the political and religious powers of the Nara era while advancing a new order of royal authority. The move to Heian-kyō in 794 is generally regarded as the event symbolizing the beginning of the Heian period.
Later historical narratives portray Empress Shōtoku's relationship with Dōkyō as a cautionary tale of female rule, religious influence, and political disorder. Recent scholarship has reassessed this narrative, emphasizing her independent political authority and the seriousness of Fujiwara no Nakamaro's rebellion. The traditional story should be treated as both historical evidence and a product of the political values of the period in which it was recorded.
From the second half of the ninth century onward, the Northern Fujiwara branch came to hold great influence at court centered on the positions of Sesshō (regent) and Kampaku, strengthening that position through marriage ties to the emperor.
Michizane rose through the trust of Emperors Uda and Daigo and became Minister of the Right in 899. In 901, however, he was accused by Fujiwara no Tokihira and others and demoted to Dazaifu.
Consolidated imperial authority and court administration. In the Kusuko Incident of 810, he contained the moves of the retired Emperor Heizei's side and brought the conflict over the succession to a close. His reign also saw important developments in court institutions and culture.
Sought to advance court politics independent of the Fujiwara, relying on figures such as Sugawara no Michizane. His reign is an important example of imperial attempts to balance aristocratic power, although the later Fujiwara regency system remained resilient.
The Fujiwara increasingly strengthened their influence by marrying daughters into the imperial family and serving as regents for young sovereigns. Emperors could retain substantial political and religious authority, however, and the relationship between the throne and the regents was one of negotiation as well as control.
The first emperor in some 170 years whose mother was not a Fujiwara — the first since Emperor Uda. From a position less exposed to the influence of the Fujiwara regent house, he pursued imperial government, carrying out measures such as the land-reclamation orders and the establishment of the Record of Estates and Contracts Bureau. He also influenced the configuration of imperial succession that would later connect to Cloistered Rule (Insei).
The Fujiwara regency system did not simply replace imperial government with aristocratic rule. Emperors retained important religious, ceremonial, and political authority, while Fujiwara regents gained extraordinary influence through marriage alliances and control of court offices. The balance varied by reign and depended on the personalities and resources of both the sovereign and the regent.
From the Soga to the Fujiwara, and from aristocratic government to warrior rule: Japan's political power did not simply pass from one force straight to the next — it changed while the relationships among royal power, the aristocracy, temples and shrines, and the warriors were rearranged.
The Isshi Incident of 645 is one such turning point in that long change. After the main line of the Soga fell, the Fujiwara came to be deeply involved in court politics through marriage with the imperial family and through offices such as Sesshō and Kampaku. But the emperor's authority did not itself disappear: in the Heian court, negotiation and the redistribution of power continued between the emperor and the regent house.
From the later eleventh to the twelfth century, Cloistered Rule and the rise of the warriors changed the political structure further. Beyond that lies the run of Japanese political history leading to the Kamakura shogunate, the Muromachi shogunate, the Toyotomi regime, and the Tokugawa shogunate.
When you walk through Osaka Castle, you need not look only at the stone walls and moats in front of you. Behind them lies more than a thousand years of political history: who sustained royal authority, who held the land and military power, and who recorded "legitimate politics."
If you'd like to see how that same struggle for power played out centuries later between Hideyoshi and Ieyasu, Before Japan had a Name follows that story across the very ground where it unfolded.
The Soga–Fujiwara struggle for the imperial line was fought across the early capitals of Asuka, Naniwa, and Nara — the same high ground that Osaka Castle stands on today.
Walk with a historian who lives beside it. Small groups. Osaka Castle every day • English • Max 6 guests
Book Goddess, Queen, Empress, Concubine Call / Text Edward WhatsApp EdwardLast updated: October 2026
Edward Iftody — Osaka Castle’s Resident Historian
Research by Edward Iftody, Osaka-based historian and resident historian at Osaka Castle.
This reconstruction draws on contemporary European accounts, Japanese archaeological research, historical geography, and the surviving physical landscape.
