Background
Takakazu Seki was the second son of Uchiyama Shichibei, a retainer of the shogunate, and is said to have been born at Fujioka in Kozuke, present-day Gumma Prefecture on March 1642; his father was later adopted into the Seki family.
His father served Tokugawa Tsuna- toyo, lord of the castle of Kofu, and later, when Tsunatoyo was adopted as heir to the fifth shogun, Tsunayoshi, Takakazu became a samurai under the direct jurisdiction of the shogunate, being assigned to the post of onando kumigashira, the office in charge of clothing and furnishings for the shogun.