Emperor Kaika

, also known as in the "Kojiki", and in the "Nihon Shoki" was the ninth 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. Kaika 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. Kaika's reign allegedly began in 158 BC, he had one wife and three consorts of which he fathered five children with. After his death in 98 BC, one of his sons supposedly became the next emperor.
Legendary narrative.
In the "Kojiki" and "Nihon Shoki", only Kaika's name and genealogy were recorded. The Japanese have traditionally accepted this sovereign's historical existence, and an Imperial "misasagi" or tomb for Kaika is currently maintained; however, no extant contemporary records have been discovered that confirm a view that this historical figure actually reigned. Kaika was born sometime in 208 BC, and is recorded as being the second son of Emperor Kōgen. His empress mother was named "Utsushikome", who was the daughter of "Oyakuchisukune". Before he was enthroned sometime in 158 BC, his pre-ascension name was "Prince Nikohiko Ō-hibi no Mikoto". The Kojiki records that he ruled from the palace of at Karu in what would come to be known as Yamato Province. Emperor Kaika had a chief wife (empress) named "Ikagashikome", along with three consorts of which he fathered five children with. Kaika ruled until his death in 98 BC; his second son was then enthroned as the next emperor. His son/heir to the throne was posthumously named "Sujin" by later generations, and is the first emperor that historians say might have actually existed.
Known information.
The existence of at least the first nine Emperors is disputed due to insufficient material available for further verification and study. Kaika is thus regarded by historians as a "legendary Emperor", and is considered to have been the eighth of eight Emperors without specific legends associated with them. The name Kaika"-tennō" was assigned to him posthumously by later generations.
 His name might have been regularized centuries after the lifetime ascribed to Kaika, possibly during the time in which legends about the origins of the Yamato dynasty were compiled as the chronicles known today as the "Kojiki". While the actual site of Kaika's grave is not known, the Emperor is traditionally venerated at a memorial Shinto shrine ("misasagi") in Nara. The Imperial Household Agency designates this location as Kaika's mausoleum, and its formal name is "Kasuga no Izakawa no saka no e no misasagi".
Like Emperor Kōshō and Emperor Kōrei, there is a possibility that "Kaika" could have lived instead in the 1st century (AD). Historian Louis Frédéric notes this idea in his book "Japan Encyclopedia" where he says "more likely early AD", but this remains disputed among other researchers. 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.
Consorts and children.
Empress: , Oohesoki's daughter
Consort: , Taniwa no Ooagatanushi Yugori's daughter
Consort: , Prince Waninishisaihito's daughter
Consort: , Katsuragi no Tarumi no Sukune's daughter
Further reading.
 