Tenkai was a Japanese TendaiBuddhist monk of the Azuchi-Momoyama and early Edo periods. He achieved the rank of Daisōjō, the highest rank of the priesthood. His Buddhist name was first Zuifū, which he changed to Tenkai in 1590. Also known as Nankōbō Tenkai, he died in 13 November 1643, and was granted the posthumous title of Jigen Daishi in 1648. Tenkai was at Kita-in in Kawagoe in 1588, and became abbot in 1599. He was on the advisor of Tokugawa Ieyasu, and served as a liaison between the Tokugawa Shogunate and the Imperial Court in Kyoto. One of his projects was the rebuilding of Enryaku-ji, which had been devastated by Oda Nobunaga. He also revitalized Kita-in, and changed the characters of its name to 喜多院. Nearing death in 1616, Ieyasu entrusted Tenkai with his last will regarding matters of his funeral and his posthumous name. Tenkai selected gongen rather than myōjin, and after death Ieyasu became known as Tōshō Daigongen. Tenkai continued to serve as a consultant to the next two Tokugawa shōguns. In 1624, retired shōgun Tokugawa Hidetada and ruling shōgun Tokugawa Iemitsu asked him to establish Kan'ei-ji, a Buddhist temple to the northeast of Edo Castle in Ueno. There are several theories concerning his early life. Some fiction writers postulate that he was in actuality Akechi Mitsuhide. It is not certain whether Mitsuhide died at the Battle of Yamazaki or not, and some suppose that he survived and began a new life as the priest Tenkai.
Tenkai appears as the main villain in the first Sakura Wars game.
In the gameSengoku Basara 3 and the anime the character Tenkai is portrayed as a cryptic monk who speaks in riddles and wields twin scythes. As with the rumor above, Tenkai is actually a re-skinned model of Akechi Mitsuhide, from the game and anime's predecessor. As of the UTAGE upgrade of the third game, the series established both Tenkai and Mitsuhide as a same person.
In the anime and light novelsMirage of Blaze, Tenkai's name has been mentioned in a crucial part of the story arc, being that an old incantation of his that he had invoked centuries ago would be the key for Lord Kagetora Uesugi and his team to stop their enemies in controlling the Feudal Underworld and the living world.
He appears in the mobile gameFate/Grand Order as an antagonist of the event GUDAGUDA Imperial Capital Grail. He is truly Akechi Mitsuhide and he quickly reveals his identity.
