The were a set of four emperors (Emperor Go-Daigo and his line) whose claims to sovereignty during the Nanboku-chà  period spanning from 1336 through 1392 were usurped by the Northern Court. This period ended with the Southern Court definitively losing the war, and they were forced to completely submit sovereignty to the Northern Court. This had the result that, while later Japanese sovereigns were descended from the Northern Court, posterity assigns sole legitimacy during this period to the Southern Court.
The Southern descendants are also known as the "junior line" and the , Daikaku-ji being the cloistered home of Go-Uda, a Southern ruler. Because it was based in Yoshino, Nara, it is also called the .
The genesis of the Northern Court go back to Emperor Go-Saga, who reigned from 1242 through 1246. Go-Saga was succeeded by two of his sons, Emperor Go-Fukakusa and Emperor Kameyama, who took turns on the throne. This was because on his death bed in 1272, Go-Saga had insisted that his sons adopt a plan in which future emperors from the two fraternal lines would ascend the throne in alternating succession. This plan proved to be unworkable, resulting in rival factions and rival claimants to the throne.
In 1333, when the Southern Emperor Go-Daigo staged the Kenmu Restoration and revolted against the Kamakura shogunate, the shà Âgun responded by declaring Emperor Kà Âgon, Go-Daigo's second cousin once removed and the son of an earlier emperor, Emperor Go-Fushimi of the Jimyà Âin-tà Â, as the new emperor. After the destruction of the Kamakura shogunate in 1333, Kà Âgon lost his claim, but his brother, Emperor Kà Âmyà Â, and two of his sons were supported by the new Ashikaga shà Âguns as the rightful claimants to the throne. Kà Âgon's family thus formed an alternate Imperial Court in Kyoto, which came to be called the Northern Court because its seat was in a location north of its rival.
During the Meiji period, an Imperial decree dated April 3, 1911 established that the legitimate reigning monarchs of this period were the direct descendants of Emperor Go-Daigo through Emperor Go-Murakami, whose Southern Court had been established in exile in Yoshino, near Nara.
The Northern Court established in Kyoto by Ashikaga Takauji is therefore considered illegitimate.
These are the Hokuchà  or Northern Court emperors:
The Imperial Court supported by the Ashikaga shà Âguns was rivaled by the Southern Court of Go-Daigo and his descendants. This came to be called the Southern Court because its seat was in a location south of its rival. Although the precise location of the emperors' seat did change, it was often identified as simply Yoshino.
In 1392, Emperor Go-Kameyama of the Southern Court was defeated and abdicated in favor of Kà Âgon's great-grandson, Emperor Go-Komatsu, thus ending the divide. But the Northern Court was under the power of the Ashikaga shà Âguns and had little real independence. Partly because of this, since the 19th century, the Emperors of the Southern Imperial Court have been considered the legitimate Emperors of Japan. Moreover, the Southern Court controlled the Japanese imperial regalia. The Northern Court members are officially called pretenders.
One Southern Court descendant, Kumazawa Hiromichi, declared himself to be Japan's rightful Emperor in the days after the end of the Pacific War in World War II. He claimed that Emperor Hirohito was a fraud, arguing that Hirohito's entire line is descended from the Northern Court. Despite this, he was not arrested for lèse-majesté, even when donning the Imperial Crest. He could and did produce a koseki detailing his bloodline back to Go-Daigo in Yoshino, but his claims and rhetoric failed to inspire anything other than sympathy.
These are the Nanchà  or Southern Court emperors:
Go-Kameyama reached an agreement with Go-Komatsu to return to the old alternations on a ten-year plan. However, Go-Komatsu broke this promise, not only ruling for 20 years, but being succeeded by his own son, rather than by one from the former Southern Court.