Appointment of the Saio
A new Saio was appointed each time a new emperor came to the throne. When the emperor abdicated or passed away, the Saio retired.
The Saio system is thought to have originated in the second half of the seventh century. The earliest known Saio was Princess Oku (661–701). Oku’s father was Emperor Tenmu, credited with establishing the first centralized government in ancient Japan. The Saio system lasted until the first half of the 14th century, resulting in the appointments of over 60 Saio over a period of about 660 years.
The newly appointed Saio spent an entire year secluded from the secular world in a room within the imperial palace. She then moved to a temporary palace built on the outskirts of the capital, where she spent another year isolated from the secular world. Her subsequent relocation to Ise, where the Saiku was situated, usually took place two or three years after her appointment.