Tenkai was a Tendai Buddhist monk who achieved the highest rank of the priesthood and became abbot of Kita-in at Kawagoe in 1588. He served Tokugawa Ieyasu as liaison between the Tokugawa Shogunate and the Imperial Court at Kyoto. After Ieyasu's death in 1616, he also served the 2nd Tokugawa Shogun, Tokugawa Hidetada, and the 3rd, Tokugawa Iemitsu. Among his projects were the rebuilding of Enryaku Temple on Mount Hiei, the restoration of Rinnou Temple in Nikkou, and the establishment of Kan'ei-ji in Ueno.