Fujiwara no Kamatari was the founder of the Fujiwara clan in Japan. His birth clan was the Nakatomi. He was the son of Nakatomi no Mikeko, and his birth name was Nakatomi no Kamatari. Just before his death, he received the surname Fujiwara from Emperor Tenji.
He was a friend and supporter of the Prince Naka no Ooe, later Emperor Tenji. Kamatari was the head of the Jingi no Haku, or Shinto ritualists; as such, he was one of the chief opponents of the increasing power and prevalence of Buddhism in the court, and in the nation. As a result, in 645, Prince Naka no Ooe and Kamatari made a coup d'etat in the court. They slew Soga no Iruka who had a strong influence over Empress Kougyoku; thereafter, Iruka's father, Soga no Emishi, committed suicide.
Empress Kougyoku was forced to abdicate in favor of her younger brother, who became Emperor Koutoku; Koutoku then appointed Kamatari naidaijin (Inner Minister). He then went on to help write the Taika Reforms, a major set of reforms based on Chinese models and aimed at strengthening Imperial power.
During his life Kamatari continued to support Prince Naka no Ooe, who became Emperor Tenji in 661. Tenji granted him the highest rank Taishokan and a new clan name, Fujiwara, as honors.
His son was Fujiwara no Fuhito. Kamatari's nephew, Nakatomi no Omimaro became head of Ise Shrine, and passed down the Nakatomi name.
In the 13th century, the main line of the Fujiwara family split into five houses: Konoe, Takatsukasa, Kujou, Nijou and Ichijou. These five families in turn provided regents for the Emperor, and were thus known as the Five Regent Houses. The Tachibana clan also claim descent from the Fujiwara. Emperor Montoku of the Taira clan was descended through his mother of the Fujiwara.
Until the marriage of the Crown Prince Hirohito (posthumously Emperor Showa) to Princess Kuni Nagako (posthumously Empress Koujun) in January 1924, the principal consorts of emperors and crown princes had always been recruited from one of the Sekke Fujiwara. Imperial princesses were often married to Fujiwara lords - throughout a millennium at least. As recently as Emperor Showa's third daughter, the late former Princess Takanomiya, and Prince Mikasa's elder daughter, the former Princess Yasuko, married into Takatsukasa and Konoe families, respectively. Empress Shouken was a descendant of the Fujiwara clan and through Hosokawa Gracia of the Minamoto clan. Likewise a daughter of the last Tokugawa Shogun married a second cousin of Emperor Showa.
Three unifiers of Japan were related to the Fujiwara: ・Oda Nobunaga's great-grand niece married into the Fujiwara. ・Toyotomi Hideyoshi's second wife was distantly related by marriage to the Fujiwara. ・Tokugawa Ieyasu's heirs married into the Fujiwara.