Emperor Shirakawa was born in 1053 to Emperor Go-Sanjô and the posthumously appointed dowager empress Fujiwara no Mochiko. He reigned as Tennô from 1072 until 1086, at which time he abdicated in favor of his son Horikawa. He was the first to abdicate and continue to take an active role in politics as In, and he set the precedent that both Toba and Go-Shirakawa would follow.
During his fourteen years on the throne, Shirakawa was an active participant in government decision-making. The influence of the Fujiwara clan, which had dominated court decisions, was much reduced by Go-Sanjô's efforts to increase the power of the imperial house. As a result, Shirakawa was able to exercise much more control over court matters, most notably the regulation of landholdings. Despite this increase in imperial authority, it seems that Shirakawa wished to make the imperial house even more of a political force, and one in which his direct descendants could accede to the throne (Hurst, 1976, p 130).
When the opportunity presented itself for him to place his son on the throne, he took it, although he spent several months deliberating whether or not to go against his father's wishes. He named his son, Horikawa, crown prince, and abdicated on the same day. For the first several years of his tenure as In, Shirakawa was not very active in matters of government. Rather, he was making social and ceremonial calls, and apparently making full use of the freedom that he was not afforded as Tennô. It was not until after the deaths of two of the heads of the Fujiwara family that Shirakawa began to take a truly active role in politics. The deaths of Morozane and Moromichi left the Fujiwara house under the control of a young, relatively inexperienced Tadazane. The resulting gap in the political power structure was filled by Shirakawa, who apparently enjoyed a great deal of power, influencing many appointments and continuing to control governance of private landholdings. However, he exercised this power "through the established channels of . . . government" (Hurst, 1974, p 74). So Shirakawa set the precedent for the two other powerful In to follow.