, also known as or , was the 15th (possibly legendary) Emperor of Japan, according to the traditional order of succession. Both the Kojiki and the Nihon Shoki record events that took place during à Âjin's alleged lifetime. à Âjin is traditionally listed as the first emperor of the Kofun period, and is primarily known for being the controversial son of Empress Jingà «. Historians have mixed views on his factual existence; if à Âjin was indeed a historical figure, then it is assumed he reigned much later than he is attested.
No firm dates can be assigned to à Âjin's life or reign, but he is traditionally considered to have reigned from 270 to 310. According to the Shinto religion and Buddhism in Japan, Emperor à Âjin is the divine spirit of the deity Hachiman (). While the location of à Âjin's grave (if any) is unknown, he is traditionally venerated at a memorial Shinto tomb. Modern historians have come to the conclusion that the title of "Emperor" and the name "à Âjin" was used by later generations to describe this possibly legendary Emperor.
The Japanese have traditionally accepted this sovereign's historical existence, and a mausoleum (misasagi) for à Âjin is currently maintained. The following information available is taken from the pseudo-historical Kojiki and Nihon Shoki, which are collectively known as or Japanese chronicles. These chronicles include legends and myths, as well as potential historical facts that have since been exaggerated and/or distorted over time. The circumstances surrounding the future emperor's birth are controversial as they involve a supposed invasion of the Korean Peninsula as well as a biologically impossible gestation period (3 years). It is said by the Kiki that à Âjin was conceived but unborn when his father Emperor Chà «ai died. Empress Jingà « then became a de facto ruler who allegedly invaded a "promised land" (Korea) out of revenge, then returned three years later to the Japanese mainland to give birth. The records state that à Âjin was born to Empress Jingà « in Tsukushi Province sometime in 201 AD, and was given the name . He became the crown prince at the age of four, but was not crowned Emperor until 270 AD at the age of 70. Emperor à Âjin supposedly lived in two palaces which are now located in present-day Osaka. His reign lasted 40 years until his death in 310 AD, in all he fathered 28 children with one spouse and ten consorts. His fourth son à Âosazaki was later enthroned as the next emperor in 313 AD.
While the historical existence of Emperor à Âjin is debated among historians, there is a general consensus that he was "probably real". There is also an agreement that Ojin's three year conception period is mythical and symbolic, rather than realistic. William George Aston has suggested that this can be interpreted as a period of less than nine months containing three "years" (some seasons), e.g. three harvests. If à Âjin was an actual historical figure then historians have proposed that he ruled later than attested. Dates of his actual reign have been proposed to be as early as 370 to 390 AD, to as late as the early 5th century AD. At least one Japanese historian has cast doubt on this theory though, by revising a supporting statement given in 1972. In this new narrative Louis Perez states: "only kings and emperors after the reign of Ojin... ...are seen as historical figures". In either case there is also no evidence to suggest that the title tennà  was used during the time to which à Âjin's reign has been assigned. It is certainly possible that he was a chieftain or local clan leader, and that the polity he ruled would have only encompassed a small portion of modern-day Japan. The name à Âjin-tennà  was more than likely assigned to him posthumously by later generations.
While the actual site of à Âjin's grave is not known, this regent is traditionally venerated at a kofun-type Imperial tomb in Osaka. The Imperial Household Agency designates this location as à Âjin's mausoleum, and is formally named Eega no Mofushi no oka no misasagi. At some point à Âjin was made a guardian Kami of the Hata clan, and is now also deified as Hachiman Daimyà Âjin. Outside of the Kiki, the reign of Emperor Kinmei ( â 571 AD) is the first for which contemporary historiography has been 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.
Emperor à Âjin's family allegedly consisted of 28 children, which include 2 unnamed princesses from a previous marriage. He had one spouse who bore him a son that would become the next Emperor, as well as 10 consorts.