In Japanese history, Sesshō (literally "surrogate governor") was the title given to a regent temporarily ruling in place of a child emperor (or occasionally, an female empress).
Originally, the Sesshō was supposed to be a member of the Imperial Family, and all of the earliest Sesshō were close relatives of the emperor, such as an uncle or a cousin.
The earliest recorded Sesshō was the Emperess-Consort Jingu, who according to the quasi-mythological Kojiki chronicle, ruled on behalf of her son, Emperor Ōjin, from AD 209 to 269. The earliest know historically verifiable Sesshō was the legendary statesman Prince Shotoku, who ruled on behalf of his aunt, Empress Suiko, from AD 594 until his death in 621.
From the mid-9th century, the Fujiwara clan of nobles came to dominate the position of Sesshō, using it in combination with another title of their own creation, Kampaku (関白, regent for an adult emperor), to legitimate their rule over Japan for more than two centuries.
In 858, Fujiwara Yoshifusa became the first person to hold the title of Sesshō who was not a member of the Imperial Family. Thereafter, a tradition emerged wherein only direct descendants of the Fujiwara family could hold the title. Although eventually the title ceased to have any real political meaning, it continued to be dutifully filled by a Fujiwara descendant whenever there was a child emperor on the throne for many centuries.
The last Sesshō was Nijō Nariyuki, who held the post for a few months in 1867, until the Meiji Restoration wiped away many of the old ranks of the nobility.