Emperors of Japan in the context of "Supreme Court of Japan"

The Heian period (平安時代, Heian jidai) is the last division of classical Japanese history, running from 794 to 1185. It followed the Nara period, beginning when the 50th emperor, Emperor Kammu, moved the capital of Japan to Heian-kyō (modern Kyoto). Heian (平安) means 'peace' in Japanese. It is a period in Japanese history when the Chinese influences were in decline and the national culture matured. The Heian period is also considered the peak of the Japanese imperial court, noted for its art, especially poetry and literature. Two syllabaries unique to Japan, katakana and hiragana, emerged during this time. This gave rise to Japan's famous vernacular literature, with many of its texts written by court ladies who were not as educated in Chinese as their male counterparts.

Although the Imperial House of Japan had power on the surface, the real power was in the hands of the Fujiwara clan, a powerful aristocratic family who had intermarried with the imperial family; most Emperors of the Heian era had mothers from the Fujiwara family. The economy mostly existed through barter and trade due to the lack of a national currency, while the shōen system encouraged the growth of aristocratic estates that began gradually asserting their independence from Imperial control. Despite a lack of serious warfare or domestic strife during the Heian era, crime and banditry were widespread as the Emperors failed to police the country effectively.

Minamoto (源; Japanese pronunciation: [mʲi.na.mo.to]) was a noble surname bestowed by the Emperors of Japan upon members of the imperial family who were excluded from the line of succession and demoted into the ranks of the nobility since 814. Several noble lines were bestowed the surname, the most notable of which was the Seiwa Genji, whose descendants established the Kamakura and Ashikaga shogunates following the Heian era. The Minamoto was one of the four great clans that dominated Japanese politics during the Heian period in Japanese history—the other three were the Fujiwara, the Taira, and the Tachibana.

In the late Heian period, Minamoto rivalry with the Taira culminated in the Genpei War (1180–1185 AD). The Minamoto emerged victorious and established Japan's first shogunate in Kamakura under Minamoto no Yoritomo, who appointed himself as shōgun in 1192, ushering in the Kamakura period (1192–1333 AD) of Japanese history. The name "Genpei" comes from alternate readings of the kanji "Minamoto" (源 Gen) and "Taira" (平 Hei).

Empress Jingū (神功皇后, Jingū Kōgō) was a legendary Japanese empress who ruled as a regent following her husband's death in 200 AD. Both the Kojiki and the Nihon Shoki (collectively known as the Kiki) record events that took place during Jingū's alleged lifetime. Legends say that after seeking revenge on the people who murdered her husband, she then turned her attention to a "promised land." Jingū is thus considered to be a controversial monarch by historians in terms of her alleged invasion of the Korean Peninsula. This was in turn possibly used as justification for imperial expansion during the Meiji period. The records state that Jingū gave birth to a baby boy named Homutawake three years after he was conceived by her late husband.

Jingū's reign is conventionally considered to have been from 201 to 269 AD, and was considered to be the 15th Japanese imperial ruler until the Meiji period. Modern historians have come to the conclusion that the name "Jingū" was used by later generations to describe this legendary Empress. It has also been proposed that Jingū actually reigned later than she is attested. While the location of Jingū's grave (if any) is unknown, she is traditionally venerated at a kofun and at a shrine. It is accepted today that Empress Jingū reigned as a regent until her son became Emperor Ōjin upon her death. She was additionally the last de facto ruler of the Yayoi period.