When Nobumasa was born, he was called
Okudaira Sadamasa (奥平 貞昌). Tokugawa allowed Nobumasa to marry his eldest daughter,
Kamehime; and he was given Nagashino Castle. Sadamasa was entrusted with the defense of
Nagashino Castle by
Tokugawa Ieyasu. Sadamasa's decision to remove himself and his forces from the Takeda supporters became one of the antecedents of the
Battle of Nagashino in 1575. Katsuyori was enraged at Sadamasa's decision to leave the Takeda forces. Nagashino Castle was attacked by Katsuyori with a force of 15,000 troops; but Sadamasa held firm, repelling the Takeda siege until forces of a Tokugawa-Oda alliance eventually arrived to support the beleaguered Okudaira. Oda Nobunaga was so impressed by the Okudaira's performance in the battle that he offered Sadamasa the honor of adopting part of his name—Nobu. After the battle was won, the hardy warrior was changed from Sadamasa to Nobumasa. When Nobumasa completed his service as
Kyoto shoshidai in 1601, he was transferred to
Kanō Domain in
Mino Province. He built
Kanō Castle in
Gifu,
Gifu Prefecture, and commissioned the building of
Kanō Tenman-gū. In 1602, he retired in Kano and handed over the position of the lord of the
Kano Castle to the third son
Okudaira Tadamasa. In 1614, he outlived Tadamasa and even the first son
Okudaira Iemasa in
Utsunomiya Domain at
Shimotsuke Province, in 1615 the following year he died. ==Daihannya sword==