Why did the Fujiwara family encourage emperors to abdicate at young ages?

The Fujiwara family encouraged emperors to abdicate at young ages primarily to consolidate their own political authority through the regency system. By placing child emperors on the throne, the Fujiwara clan could act as regents, effectively serving as the de facto rulers of Japan.1

This strategy allowed the family to maintain a firm grip on the government, as the regent held significant power while the young monarch was unable to exercise independent authority. The Fujiwara further solidified this control by ensuring that their own daughters were married to emperors, meaning the child emperors were often their grandsons or nephews.12

While the Fujiwara initially used this practice to dominate the court, it was a double-edged sword; later, independent-minded emperors adopted the practice of "cloistered rule" (insei), where they would abdicate to a monastery to escape Fujiwara oversight and continue to rule from behind the scenes, eventually contributing to the decline of Fujiwara influence.13