kampaku

Kampaku (関白) is a regent in the Japanese imperial court who acts on behalf of the emperor, specifically for an adult emperor. It is the counterpart to sesshō (摂政), the regent for a minor emperor. The kampaku and sesshō are part of the sekkan system (摂関政治) that governed the Heian court. The office emerged in the late 8th or early 9th century and was normally held by members of the Fujiwara clan, especially the Hokke (Northern House). By enlarging the regency, Fujiwara strengthened control over the government while leaving the emperor as a nominal head.

During the Heian period, kampaku became the dominant form of regent, with the power to appoint officials, conduct diplomacy, and direct state affairs. One of the most famous kampaku was Fujiwara no Michinaga (c. 966–1027), whose influence helped consolidate the Fujiwara's political supremacy; his period is often cited as the height of sekkan power. However, the rise of military rulers later in medieval Japan eventually reduced the political importance of the court and its regents; the office continued in name but with diminished authority as real power shifted to shoguns.

In practice, kampaku and sesshō were tools for the Fujiwara to control the throne across multiple generations, shaping court life, governance, and diplomacy in Japan's classical era. The term remains a central concept in studies of Heian politics and the broader history of the imperial regency system.