Emperor Tenji was the 38th emperor of Japan according to the traditional order of succession. Initially known as Prince Kazuraki, and later Prince Naka no Ōe, he was the son of Emperor Jomei and Empress Kōgyoku. After his father's death in 641, the young Prince Naka entered into a succession dispute with another imperial prince, Yamashiro. To mediate, Empress Kōgyoku ascended the throne. Naka conspired with a group of aristocrats to assassinate the authoritarian minister Soga no Iruka in 645. After the assassination, Kōgyoku resigned as ruler and was succeeded by her brother, Emperor Kōtoku, who appointed Naka as his heir. However, after Kōtoku's death in 654, Kōgyoku reascended the throne as Empress Saimei. She died in 661 amid preparations for an expedition to Korea, where the forces of Tang China and Silla defeated those of Japan. Prince Naka did not immediately ascend to the throne, instead serving as regent for the following seven years.