Before his ascension to the Chrysanthemum Throne, his personal name was Hatsusebe-shinnō, also known as Hatsusebe no Waka-sazaki. His name at birth was Hatsusebe. He was the twelfth son of Emperor Kinmei. His mother was Soga no Oane, a daughter of Soga no Iname, who was the chief, or Ōomi, of the Soga clan. He succeeded his half-brother, Emperor Yōmei in 587, and lived in the Kurahashi Palace in Yamato.
587: In the 2nd year of Yōmei-tennō's reign, the Emperor died, and despite a dispute over who should follow him as sovereign, the succession was received by another son of Emperor Kinmei, one of Yōmei's younger brothers. Shortly thereafter, Emperor Sushun is said to have acceded to the throne.
Sushun's contemporary title would not have been tennō, as most historians believe this title was not introduced until the reigns of Emperor Tenmu and Empress Jitō. Rather, it was presumably Sumeramikoto or Amenoshita Shiroshimesu Ōkimi, meaning "the great king who rules all under heaven". Alternatively, Sushun might have been referred to as or the "Great King of Yamato". He came to the throne with the support of the Soga clan and Empress Suiko, his half sister and the widow of Emperor Bidatsu. Initially, the Mononobe clan, a rival clan of the Sogas, allied with Prince Anahobe, another son of Kimmei, and attempted to have him installed as Emperor. At the Battle of Shigisan, Soga no Umako, who succeeded his father as Ōomi of the Soga clan, eventually killed Mononobe no Moriya, the head of the Mononobe clan, which led to its decline. Umako then installed Emperor Sushun on the throne. As time went on, Sushun eventually became resentful of Umako's power, and wanted him deposed. It is said that one day, he saw a wild boar and proclaimed, "I want to kill Soga Umako like this wild boar". This angered Soga no Umako and, perhaps out of fear of being struck first, Umako had Sushun assassinated by Yamato no Aya no Koma in 592. Emperor Sushun's reign lasted for five years before his death at the age of 72. The actual site of Sushun's grave is known. The Emperor is traditionally venerated at a memorialShinto shrine at Nara. The Imperial Household Agency designates this location as Yōmei's mausoleum. It is formally named Kurahashi no oka no e no misasagi.
