, also known as was the fifth legendary emperor of Japan, according to the traditional order of succession. Very little is known about this Emperor due to a lack of material available for further verification and study. Kōshō is known as a "legendary emperor" among historians as his actual existence is disputed. Nothing exists in the Kojiki other than his name and genealogy. Kōshō's reign allegedly began in 475 BC, he had one wife and two sons. After his death in 393 BC, his second son supposedly became the next emperor.
Legendary narrative
In the Kojiki and Nihon Shoki, only his name and genealogy were recorded. The Japanese have traditionally accepted this sovereign's historical existence, and an Imperial misasagi(陵) or tomb for Kōshō is currently maintained; however, no extant contemporary records have been discovered that confirm a view that this historical figure actually reigned. Kōshō is believed to be the oldest son of Emperor Itoku, and his wife Amanotoyototsu-hime. His mother was the daughter of Okishimimi-no-kami. The Kojiki records that he ruled from the palace of at Waki-no-kami in what would come to be known as Yamato Province. Kōshō is thus regarded by historians as a "legendary Emperor", and is considered to have been the fourth of eight Emperors without specific legends associated with them. The name Kōshō-tennō was assigned to him posthumously by later generations, and literally means "filial manifestation". His name might have been regularized centuries after the lifetime ascribed to Kōshō, possibly during the time in which legends about the origins of the imperial dynasty were compiled as the chronicles known today as the Kojiki.
The first emperor that historians state might have actually existed is Emperor Sujin, the 10th emperor of Japan. Outside of the Kojiki, the reign of Emperor Kinmei ( – 571 AD) is the first for which contemporary historiography is able to assign verifiable dates. The conventionally accepted names and dates of the early Emperors were not confirmed as "traditional" though, until the reign of Emperor Kanmu between 737 and 806 AD.