Two other wives of Nobuyuki were his first wife and cousin Seiin-in, who lost her status to Komatsuhime and Ukyo (a daughter of Tamagawa Hidemasa).

In 1585, Tokugawa Ieyasu attacked Ueda Castle; Nobuyuki fought in Battle of Kami river alongside his father and was victorious.

During the Battle of Sekigahara, he fought on the side of Tokugawa Ieyasu (Eastern Army), against whom Masayuki and his brother, Yukimura were fighting.

After the Western Army was defeated by Ieyasu, Nobuyuki used this position to save his father's and brother's lives.

Accepting the truth, Nobuyuki couldn't spare Sanada Yukimura again and his brother was killed in battle.