Suiko ruled Japan from 592 to 628 c.e. alongside her regent, the crown prince Shotoku Taishi. She was the daughter of Emperor Kimmei and his consort, a woman from the powerful Soga clan. After Kimmei’s death his son Bidatsu took the throne, and Suiko, his half sister, became his wife.

Bidatsu soon died, and another of Suiko’s brothers, Yomei, became sovereign until his death two years later. A subsequent power struggle over the throne ended in victory for the Soga as Sushun, one of Suiko’s half brothers, took the throne.

However, the head of the Soga clan, Umako, did not trust Sushun’s growing resentment toward the Soga, and Umako had him assassinated in 592 c.e. After his murder Umako asked her to accept the throne, which she conceded. Shôtoku became her regent and coruler.

Scholars used to emphasize Shôtoku’s role over Suiko’s in the governing of Japan, stating that Suiko merely served as the head priestess of the court kami worship. This is due in part to Chinese texts that focused more on Shôtoku’s activity. In Confucianism males rule over women, and thus the Japanese court may have used Shôtoku as the proper male representative in its relations with China.

It is also possible that Confucian scholars chose to write more about their interactions with the Yamato state through Shôtoku rather than Suiko. Some scholars note, however, that Suiko was active in sending the Yamato state’s first embassy to China in 600 and established relations with the Korean kingdom Silla in 621. Both Japanese and Korean sources demonstrate that Suiko was just as active as Shôtoku in her administrative rule over the Yamato state.

Suiko even asserted her rule against attempts by her uncle Soga no Umako to expand the Soga clan’s power. She rejected Umako’s request for more land, claiming that future scholars would castigate her for being a foolish woman if she allowed the Soga clan to obtain more power.

An overly powerful Soga clan encroaching on the power of the sovereign was said to be analogous to two kings in one kingdom, which was like having two Suns in the sky. Suiko’s death in 628 created a power vacuum that led to yet another showdown between the Soga and their rivals.

Crown Prince Shôtoku had died before Suiko, and Suiko died before declaring an heir. The Soga forged documents that stated Suiko preferred the Soga-backed candidate of her two remaining sons.

The forgery and authoritarian rule by the Soga, especially that of Iruka who used the military to eliminate his critics, pushed opponents to join forces in a coup. Iruka was assassinated in 645, bringing an end to Soga power.