noun
chief advisor to the Emperor; regent
Historical title for the highest-ranking official who advised the Emperor and often held de facto power, especially during the Heian period.
藤原道長は関白として絶大な権力を振るった。
Fujiwara no Michinaga wielded immense power as Kampaku.
関白は天皇の補佐役として重要な地位だった。
The Kampaku was an important position as an assistant to the Emperor.