Koan-tenno (Yamatotarashihikokuni...

https://en.wikipedia.org/wiki/Emperor_Kōan

Emperor Kōan (孝安天皇, Kōan-tennō), also known as Yamatotarashihikokunioshihito no Mikoto (大倭帯日子国押人命) was the sixth legendary emperor of Japan, according to the traditional order of succession.[4][5] Very little is known about this Emperor due to a lack of material available for further verification and study. Kōan 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. Kōan's reign allegedly began in 393 BC, he had one wife and two sons and reigned for more than 100 years until his death in 291 BC at the age of 137. One of his sons then supposedly became the next emperor.[6] Emperor Kōan is traditionally accepted as the final emperor of the Jōmon period, which ended in 300 BC.[7]