According to very scanty information from the Imperial archives, including sources such as Rikkokushi, and Nihon Sandai Jitsuroku, Emperor Yozei committed murder by killing one of his retainers, an action that caused massive scandal in the Heian court. Japanese society during the Heian era was very sensitive to issues of "pollution", both spiritual and personal. Deaths (especially killing animals or people) were the worst acts of pollution possible, and warranted days of seclusion in order to purify oneself. Since the Emperor was seen as a divine figure and linked to the deities, pollution of such extreme degree committed by the highest source was seen as extremely ruinous. Because many of the high court officials saw Emperor Yozei's actions as exceeding the bounds of acceptable behavior, he was forcibly deposed, and retired from the throne.
The original role of the sessho was to attend to affairs of state during the minority of the emperor, while the kampaku's role was to attend to state matters for the emperor even after he had come of age.
The emperor Go-Sanjo ascended the throne in 1068, the first sovereign in more than a century not born of a daughter of the Fujiwara; while Michinaga's sons Yorimichi and Norimichi both gave their daughters to be imperial consorts, no Fujiwara-related heirs resulted from these unions.
In practice, however, retired emperors seemed more concerned with the construction of ostentatious temples; temples also were endowed with shoen commended by clients of the imperial family, some of them coming to possess large numbers of estates for the support of a grand lifestyle.