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 emperor of Japan or Tennō , literally "ruler from heaven" or "heavenly sovereign", is the hereditary monarch and head of state of Japan. The emperor is defined by the Constitution of Japan as the symbol of the Japanese state and the unity of the Japanese people, his position deriving from "the will of the people with whom resides sovereign power". The Imperial Household Law governs the line of imperial succession. Pursuant to his constitutional role as a national symbol, and in accordance with rulings by the Supreme Court of Japan, the emperor is personally immune from prosecution. By virtue of his position as the head of the Imperial House, the emperor is also recognized as the head of the Shinto religion, which holds him to be the direct descendant of the sun goddess Amaterasu. According to tradition, the office of emperor was created in the 7th century BC, but the first historically verifiable emperors appear around the 5th or 6th centuries AD.