Its original responsibility was to take care of the emperor's archives and imperial documents as well as to attend to various personal needs of the sovereign. However, over the course of the 9th century, the office's role and responsibilities expanded considerably, and by the end of the 9th century it had become a clear control point within the government.
This office initially focused on managing the emperor's private papers and attending to his personal needs. However, as time passed, its responsibilities grew, transforming it into a vital center of power within the government by the late 9th century.