Emperor Hanzei

Emperor Hanzei (反正天皇, Hanzei-tennō) also known as Emperor Hansho, was the 18th Emperor of Japan, according to the traditional order of succession. Both the Kojiki, and the Nihon Shoki (collectively known as the Kiki) recorded events that took place during Hanzei's alleged lifetime. No firm dates can be assigned to this Emperor's life or reign, but he is conventionally considered to have reigned from 406 CE to 410 CE. His family included an "Imperial Lady", and "Concubine" which bore him 4 children. Historians have stated that while nothing remarkable took place during Hanzei's brief reign, he did have ranked concubines which is an introduced Chinese custom.

Hanzei died sometime in 410 AD without naming an heir to the throne which caused Imperial ministers to name a successor. While the location of Hanzei's grave 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 "Hanzei" were used by later generations to describe him. There is also a general consensus regarding Hanzei's factual existence.

Source: Wikipedia — https://en.wikipedia.org/wiki/Emperor_Hanzei