Emperor Tenji (also romanized Tenchi, 626–671) was the 38th emperor of Japan according to the traditional order of succession. Initially known as Prince Kazuraki, and later Prince Naka no Ōe, he was the son of Emperor Jomei and Empress Kōgyoku. After his father's death in 641, the young Prince Naka entered into a succession dispute with another imperial prince, Yamashiro. To mediate, Empress Kōgyoku ascended the throne. Naka conspired with a group of aristocrats to assassinate the authoritarian minister Soga no Iruka in 645. After the assassination, Kōgyoku resigned as ruler and was succeeded by her brother (Naka's uncle), Emperor Kōtoku, who appointed Naka as his heir. However, after Kōtoku's death in 654, Kōgyoku reascended the throne as Empress Saimei. She died in 661 amid preparations for an expedition to Korea, where the forces of Tang China and Silla defeated those of Japan. Prince Naka did not immediately ascend to the throne, instead serving as regent for the following seven years.
During his term as regent, Naka implemented reforms to the imperial court and built up military infrastructure in Kyushu, fearing a Chinese invasion. He moved the capital to the Ōmi Ōtsu Palace northeast of Asuka, after which he ascended to the throne as emperor. He established the (Council of State), appointing his son Prince Ōtomo as the inaugural ('prime minister'), and allegedly ordered the compilation of the first version of the law code. He fell ill and died in 671, prompting a succession dispute between Prince Ōtomo and Tenji's brother, Prince Ōama. It is unknown which Tenji wished to succeed him. The dispute broke out into a brief civil war, which ended with the victory of Ōama, who then ruled as Emperor Tenmu. Tenji was not memorialized under Tenmu's reign, but was given a burial tumulus in 700 under the reign of his daughter, Empress Jitō.
The 8th-century history chronicle Nihon Shoki dedicates relatively little coverage to Tenji's reign, although it emphasizes his importance during the reigns of his predecessors. He received poems in honor of him in the 8th-century anthologies Man'yōshū and , including a cycle of nine elegies. Tenji's reign at Ōmi was traditionally portrayed as a golden age for art and culture, although this was likely overstated by later chroniclers.
Early life Prince Kazuraki was born in 626 as the eldest son of Prince Tamura (later known as Emperor Jomei) and his consort Princess Takara (later known as Empress Kōgyoku). Two years later, the empress regnant Suiko died. This caused a succession crisis, as two of her potential successors (her nephew Prince Shōtoku and son Prince Takeda) had recently died, leaving Prince Tamura and Prince Yamashiro as the highest ranking princes. Tamura was the grandson of Emperor Bidatsu, Suiko's consort and brother, while Yamashiro was Prince Shōtoku's son. Unlike in the earlier succession crisis which brought Suiko to the throne, there were no imperial princesses in a position to serve as a neutral candidate.
The powerful Senior Minister Soga no Emishi backed Prince Tamura's candidacy, and Tamura took the throne in 629 as Emperor Jomei. However, Yamashiro continued to serve as a pretender. The Nihon Shoki, an early 8th century chronicle produced by the imperial court, first mentions Prince Kazuraki when describing Jomei's ascension. After his father's ascension, he took a new name, , likely indicating preferential status in the line of succession. However, he would not officially become the heir to the throne until 645. , part of an embassy of Japanese scholars who studied in China from 608 to 640, tutored Prince Naka on Confucian philosophy.
Emperor Jomei died in 641, beginning a succession dispute between Prince Yamashiro and Prince Naka. As the latter was only sixteen years old, he was considered too young to rule. Soga no Emishi proposed that another of Jomei's sons, Naka's half-brother Prince Furuhito no Ōji, should take the throne instead. However, Emishi was unable to secure support for this candidate. Reportedly, Naka's mother Princess Takara was instead instated, following the precedent set by Suiko, and reigned as Empress Kōgyoku. However, some scholars have theorized that there may have been an interregnum, with no sovereign until 645. The Nihon Shoki names Naka as Kōgyoku's heir, although it is more likely that Furuhito served in this position.
Isshi incident
Empress Kōgyoku had much less authority over her ministers than prior sovereigns. Some historians have theorized that this reign was a later historical fabrication, and that there was in fact no sovereign during this period. In the early 640s, Soga no Emishi's son Soga no Iruka emerged as an authoritarian political leader. The Nihon Shoki records that Iruka built palaces for himself and his father, stockpiled weapons, and began to refer to members of the clan as princes and princesses. In 642, Prince Yamashiro's sister openly criticized her brother for constructing extravagant tombs for himself and their father using forced labor. In response, Iruka dispatched a military force to attack Yamashiro's family, forcing him and thirty-two of his close relatives to commit suicide.
By 643, the Nihon Shoki relays that Iruka's activities had prompted the aristocrat Nakatomi no Kamatari to recruit conspirators to overthrow him. He approached figures such as Prince Naka, Kōgyoku's younger brother Prince Karu, and the military commander Soga no Ishikawa Maro. In reality, as a relatively low-level courtier at the time, Kamatari may have been a minor player in the plot whose importance was exaggerated by later chroniclers. In 644, the military dictator Yŏn Kaesomun overthrew and massacred the royal family of the Korean kingdom of Goguryeo, sparking a Tang invasion and likely fears among Japanese nobles that Iruka would do the same.
In the 6th month of 645, four days before a court ceremony where memorials from the Korean kingdoms would be presented to Empress Kōgyoku, Prince Naka explained to the other conspirators his plot to kill Iruka. By the day of the ceremony, Naka had the palace gates closed, bribed guards, hid a spear in the great hall, gained the support of a group of soldiers, and arranged for four men to attack Iruka during the ceremony, in what would be known as the Isshi incident.
During the ceremony, the conspirator reading out the memorials to Kōgyoku had difficulties continuing to read, and the men Naka had ordered to attack Iruka hesitated. Naka instead rushed forward and attacked Iruka with a sword, hitting him in his head and shoulder. The wounded Iruka claimed that he was innocent of the charges against him. Naka explained his case to Kōgyoku, claiming that Iruka intended to usurp the imperial throne for the Soga clan. She left the room, and Naka's assassins killed Iruka. His father, Soga no Emishi, killed himself at Hōkō-ji.
According to the Nihon Shoki, a building housing the imperial and provincial chronicles, alongside various other precious items, was set aflame during the incident. The courtier Fune no Fubito is said to have rushed into the building to save the provincial chronicles, and presented them as a gift to Prince Naka. The chronicles burned were likely compiled by Prince Shōtoku and Soga no Umako in 620, and likely had a pro-Soga bias. As such, their destruction may have been an effort by the conspirators to minimize the Soga legacy.
Heir apparent Within days of the Isshi incident, Kōgyoku abdicated, and her stepson Furuhito was sent to become a Buddhist monk. The Empress's younger brother, Prince Karu, took the throne as Emperor Kōtoku; both Kamatari and Naka have been described as the force behind Kōtoku's selection. Naka took control of state affairs, occupying a similar role to what Prince Shōtoku had taken. Kamatari became inner minister (equivalent to an advisor to the emperor), while Soga no Ishikawa Maro became minister of the right.
The post-coup government quickly implemented various reforms, beginning a decades-long transformation of the imperial government which would later be known as the Taika Reforms. The Nihon Shoki describes the reforms, which purportedly overhauled the taxation system and set the borders for the provinces. Over the course of 645, the government was said to have established a new governance system for Buddhist temple affairs, began a census and land survey, and set up a system of provincial emissaries. In an attempt to prevent future revolts, weapons were confiscated across Japan.
Also in 645, the imperial court decided to move from Asuka to the port of Naniwa-kyō in modern day Osaka, likely to have easier access to diplomatic communications. Early into the new administration, Emperor Kōtoku and Prince Naka called a meeting of the new ministers, and had them swear an oath of allegiance. The Naniwa Nagaratoyosaki palace was completed in 652, including a Chinese-style temple. The Nihon Shoki describes a falling out between Naka and Kōtoku over unspecified reasons, which led Naka and Kōgyoku to return to Asuka in 653. The chronicles cover Kōtoku's reign little, avoiding direct mention of him when describing imperial edicts; these are instead presented through Prince Naka (or other courtiers) relaying them to others. This was likely done to elevate Naka's importance with regard to the Taika Reforms.
Emperor Kōtoku died in 654, and Kōgyoku again took the throne, ruling from Asuka under the new name Empress Saimei. It is unknown why Prince Naka, the heir, was passed over in the succession. The Nihon Shoki records that Naka oversaw the construction of a water clock in Asuka in 660, the first in Japan. This had ritual and political connotations, tying the monarchy to roles of timekeeping traditionally held by Chinese sovereigns.
In late 660, the Korean kingdom of Paekche collapsed in a war against the Tang dynasty of China and the kingdom of Silla. After the Tang forces withdrew from the region, the Japanese imperial court partnered with restorations in Paekche and prepared a military expedition to restore the allied kingdom. In 661, Prince Naka visited Naniwa to manage plans for the naval expedition. Empress Saimei traveled to Tsukushi Province (in modern Fukuoka Prefecture on Kyushu) to oversee the preparations for a military expedition to Korea, accompanied by her sons Naka and Ōama as well as Kamatari. Soon after meeting with returning diplomats in Tsukushi, the Empress died.
Regency
After Saimei's death, Prince Naka became the regent, but the position of emperor was left vacant. He further mobilized the military. The Paekche prince Pung had been sent to Japan as a hostage in 631; he returned to Korea by 661 as part of a Japanese-backed movement to restore the Paekche monarchy. Japanese forces arrived in the region by 662, and restorationist rebels enthroned Pung as king. The rebels were able to secure a region around the old capital of Sabi and hold off Tang and Silla forces. In 663, the Tang and Silla navies destroyed the Japanese fleet at the mouth of the Geum River, killing many Japanese soldiers. Pung fled north to Goguryeo, and the rebellion in Paekche collapsed, leading to the loss of Japanese influence in Korea.