Emperor Ōjin , also known as Hondawake no Mikoto (誉田別尊) or Homuta no Sumeramikoto (譽田天皇), was the 15th Emperor of Japan, according to the traditional order of succession. Both the Kojiki, and the Nihon Shoki record events that took place during Ōjin's alleged lifetime. Ōjin is traditionally listed as the first emperor of the Kofun period, and is primarily known for being the controversial son of Empress Jingū. Historians have mixed views on his factual existence, if Ōjin was indeed a historical figure then it's assumed he reigned much later than he is attested.

The Kofun period is an era in the history of Japan from about 300 to 538 AD, following the Yayoi period. The Kofun and the subsequent Asuka periods are sometimes collectively called the Yamato period. This period is the earliest era of recorded history in Japan, but studies depend heavily on archaeology since the chronology of historical sources tends to be distorted. The word kofun is Japanese for the type of burial mound dating from this era.