Emperor Tenji in the context of Ōmi Ōtsu Palace

The Nihon Shoki (日本書紀) or Nihongi (日本紀), sometimes translated as The Chronicles of Japan, is the second-oldest book of classical Japanese history. It is more elaborate and detailed than the Kojiki, the oldest, and has proven to be an important tool for historians and archaeologists as it includes the most complete extant historical record of ancient Japan. The Nihon Shoki was finished in 720 under the editorial supervision of Prince Toneri with the assistance of Ō no Yasumaro and presented to Empress Genshō. The book is also a reflection of Chinese influence on Japanese civilization. In Japan, the Sinicized court wanted written history that could be compared with the annals of the Chinese.

The Nihon Shoki begins with the Japanese creation myth, explaining the origin of the world and the first seven generations of divine beings (starting with Kuninotokotachi), and goes on with a number of myths as does the Kojiki, but continues its account through to events of the 8th century. It is believed to record accurately the latter reigns of Emperor Tenji, Emperor Tenmu, and Empress Jitō. The Nihon Shoki focuses on the merits of the virtuous rulers as well as the errors of the bad rulers. It describes episodes from mythological eras and diplomatic contacts with other countries. The Nihon Shoki was written in classical Chinese, as was common for official documents at that time. The Kojiki, on the other hand, is written in a combination of Chinese and phonetic transcription of Japanese (primarily for names and songs). The Nihon Shoki also contains numerous transliteration notes telling the reader how words were pronounced in Japanese. Collectively, the stories in this book and the Kojiki are referred to as the Kiki stories.

Emperor Tenmu (also romanized Temmu, c. 630 – 686) was 40th Emperor of Japan according to the traditional order of succession. He was born Prince Ōama around 630, the son of Emperor Jomei and his consort Princess Takara. Ruling from 673 to 686, during the Asuka period, his life is mainly documented by the chronicles Nihon Shoki and Kojiki, as well as the poetry collection Man'yōshū.

Little is known of Ōama's early life. During the rule of his elder brother Tenji, Ōama was ambiguously favored as his successor, but was gradually bypassed in favor of Tenji's son Prince Ōtomo. Tenji allegedly offered Ōama the throne during an illness in 671, but fearing a conspiracy against him, Ōama declined and left to serve as a monk at Yoshino Palace. Tenji died soon after. The following year, Ōama received word that Ōtomo, now ruler, was planning to kill him. He fled Yoshino with a group of followers, beginning the Jinshin War. Along with a group of retainers and the governor of Ise Province, Ōama was able to block off the mountain passes to the northern and eastern provinces, where he raised an army against his nephew. Ōtomo was defeated and forced to commit suicide. Ōama took the throne under the name Tenmu.

The Asuka Kiyomihara Code (飛鳥浄御原令, Asuka Kiyomihara-ryō) refers to a collection of governing rules compiled and promulgated in 689, one of the first, if not the first collection of Ritsuryō laws in classical Japan. This also marks the initial appearance of the central administrative body called the Daijō-kan (Council of State) composed of the three ministers—the Daijō-daijin (Chancellor), the Sadaijin (Minister of the Left) and the Udaijin (Minister of the Right).

In 662, Emperor Tenji is said to have compiled the first Japanese legal code known to modern historians. The Ōmi-ryō, consisting of 22 volumes, was promulgated in the last year of Tenji's reign. This legal codification is no longer extant, but it is said to have been refined in what is known as the Asuka Kiyomihara ritsu-ryō of 689. The compilation was commenced in 681 under Emperor Tenmu. The Emperor died in 686, but the finalization of the Code took a few more years. It was promulgated in 689. These are understood to have been a forerunner of the Taihō ritsu-ryō of 701.

Fujiwara no Kamatari (藤原 鎌足; Japanese pronunciation: [ɸɯ.(d)ʑi.wa.ɾa no (|) ka.maꜜ.ta.ɾʲi], 614 – November 14, 669), also known as Nakatomi no Kamatari (中臣 鎌足), was a Japanese politician and aristocrat who, together with Prince Naka no Ōe (later Emperor Tenji), carried out the Taika Reform. He was the founder of the Fujiwara clan, the most powerful aristocratic family in Japan during the Nara and Heian periods. He, along with the Mononobe clan, was a supporter of Shinto and fought the introduction of Buddhism to Japan. The Soga clan, defenders of Buddhism in the Asuka period, defeated Kamatari and the Mononobe clan, and Buddhism became the dominant religion of the Imperial Court. Kamatari was appointed Inner Minister, and, along with Prince Naka no Ōe, later Emperor Tenji (626–672), launched the Taika Reform of 645, which centralized and strengthened the central government. Just before his death, he received the surname Fujiwara and the rank Taishokan [ja]

from Emperor Tenji, thus establishing the Fujiwara clan.

The Taika Reforms (大化の改新, "Taika no Kaishin; Reformation of Taika") were a set of doctrines established by Emperor Kōtoku (孝徳天皇 Kōtoku tennō) in the year 645. They were written shortly after the death of Prince Shōtoku and the defeat of the Soga clan (蘇我氏 Soga no uji), uniting Japan. The reforms also artistically marked the end of the Asuka period and the beginning of the Hakuhō period. Crown Prince Naka no Ōe (the future Emperor Tenji), Nakatomi no Kamatari, and Emperor Kōtoku jointly embarked on the details of the Reforms. Emperor Kōtoku then announced the era of "Taika" (大化), or "Great Reform".

The Reform began with land reform, based on Confucian ideas and philosophies from Tang China, but the true aim of the reforms was to bring about greater centralization and to enhance the power of the imperial court, which was also based on the governmental structure of China. Envoys and students were dispatched to China to learn seemingly everything from the Chinese writing system, literature, religion, and architecture, to even dietary habits at this time. Even today, the impact of the reforms can still be seen in contemporary Japanese cultural life.

Fujiwara no Fuhito (藤原 不比等: 659 – 13 September 720) was a powerful member of the Imperial court of Japan during the Asuka and Nara periods. Second son of Fujiwara no Kamatari (or, according to one theory, of Emperor Tenji), he had sons by two women, and those sons were the founders of the four principal lineages of the Fujiwara clan: the South, North, Ceremonial, and Capital lineages. Also, he had four daughters by two other women, three by Kamohime, one by Tachibana no Michiyo. One daughter by Kamohime became Emperor Monmu's wife Miyako, who in turn gave birth to Emperor Shōmu. The daughter by Michiyo became the empress of his grandson Shōmu, Empress Kōmyō.

During the reign of Emperor Monmu, the government ordered that only the descendants of Fuhito could bear the Fujiwara surname and could be appointed in the Office of Dajōkan, the center of administratives.

The Jinshin War (壬申の乱, jinshin no ran) was a war of succession that took place in the Yamato state near the end of Asuka period. It broke out in 672 following the death of Emperor Tenji. The name refers to the jinshin (Ch. renshen 壬申) or ninth year of the sexagenary cycle, corresponding to the Gregorian year 672. It was one of the largest conflicts in classical Japanese history.

Tenji had originally designated his brother, Prince Ōama, as his successor, but later changed his mind in favor of his son, Prince Ōtomo. In the course of the violence that erupted as a result of factional rivalries, Ōtomo, having taken the throne as emperor, killed himself after reigning for less than a year. His uncle Ōama then succeeded to the throne as Emperor Tenmu. Tenmu was the first monarch of Japan contemporaneously documented as using the title Tennō (emperor).

Nagaya (長屋王 Nagaya-no-ōkimi) (684 – 20 March 729) was a politician of the Nara period and an imperial prince of Japan, a son of Prince Takechi (grandson of Emperor Tenmu).

His father was Prince Takechi and his mother Princess Minabe (a daughter of Emperor Tenji and Empress Genmei's sister). He married Princess Kibi (his cousin, a daughter of Empress Genmei and Empress Genshō's sister).

Soga no Iruka (蘇我 入鹿) (died July 10, 645) was the son of Soga no Emishi, a statesman in the Asuka Period of Japan.

He was assassinated at court in a coup d'état involving Nakatomi no Kamatari and Prince Naka-no-Ōe (see: Isshi Incident), who accused him of trying to murder Prince Yamashiro, a charge which Soga no Iruka denied. Soga no Emishi also committed suicide soon after his son's death, and the main branch of the Soga clan became extinct. Prince Naka-no-Oe later ascended the throne as Emperor Tenji, and Nakatomi no Kamatari was promoted and given the name Fujiwara no Kamatari.