Lifespan: Daiei 1 (1521) to 7/26 of Keichō 9 (1604)
Other Names: Jūrōbei, Shinano-no-kami
Title: Junior Fifth Rank (Lower)
Lord: Tokugawa Ieyasu
Father: Suganuma Sadahiro
Mother: Adopted daughter of Ōkawachi Mototsuna
Siblings: Sadatsugu, Saemon-jirō, Sadanao, Sadauji, 定仙, sister (wife of Okudaira Sadakatsu)
Suganuma Sadauji served as a bushō during the Sengoku period.
In 1521, Sadauji was born as the fourth son of Suganuma Sadahiro. His oldest brother, Suganuma Sadatsugu, served as the fourth head of the Damine-Suganuma clan.
Sadauji served the Matsudaira (Tokugawa) clan, engaging in assorted battles. During the era of Tokugawa Ieyasu, he actively participated in battles against the Imagawa clan and served as the chamberlain of Shinshiro and Damine castles in Mikawa Province. After the demise of the Imagawa clan, many of his family members entered into service for the Takeda clan but Sadauji remained with the Tokugawa. In 1572, he served in the Battle of Mikata-ga-hara, and owing to his contributions, was granted a short-sword from a famous swordsmith from the early fourteenth century named Hasebe Kunishige in addition to landholdings in Mikawa.