Lifespan: Tenbun 17 (1548) to 8/15 of Genna 2 (1616)
Title: Governor of Iyo, Governor of Izumi
Lord: Matsudaira Ietada → Matsudaira Tadayoshi→ Tokugawa Yoshinao
Father: Ogasawara Nagataka
Mother: Daughter of Ogasawara Shigehiro
Wife: [Formal] Daughter of Kagazume Masatoyo
Children: Yoshimitsu, Nagamitsu
Ogasawara Yoshitsugu served as a daimyō in the early Edo period. He served as the head of the Owari-Inuyama domain, the Shimōsa-Sakura domain, and the Hitachi-Kasama domain. Yoshitsugu was born as the eldest son of Ogasawara Nagataka, a retainer of Matsudaira Ietada. His first name was Munetada. His mother was the daughter of Ogasawara Shigehiro. His formal wife was the daughter of Kagadume Masatoyo.
In 1575, after the demise of his father (Nagataka), Yoshitsugu continued to serve Matsudaira Ietada. Following the Battle of Sekigahara, Ietada’s successor, Matsudaira Tadayoshi (the fourth son of Tokugawa Ieyasu), acquired a fief of 520,000 koku based at Kiyosu Castle in Owari Province. Upon orders of Ieyasu, Yoshitsugu became his chief retainer and was granted territory in Inuyama. At this time, Yoshitsugu expanded Inuyama into a modern fortress and developed the town below. In 1607, after the death of Tadayoshi on 3/5 of Keichō 12 (1607), Yoshitsugu was summoned to serve in Edo. Moreover, upon the death of Tadayoshi, Yoshitsugu’s eldest son, Yoshimitsu, martyred himself at the Zōjō Temple in Edo.
Thereafter, Yoshitsugu was assigned the Shimōsa-Sakura domain of 22,000 koku, and then promoted to the Hitachi-Kasama domain of 30,000 koku. However, on 3/26 of Keichō 14 (1609), Yoshitsugu was removed from his position owing to implications of engaging in dealings for his own benefit. After returning to Edo for service, Yoshitsugu included in the value of his holdings the compensation for yoriki, or security staff, from the Kōshū-Mukawa group (of Kai Province) whom he managed while an assistant of Tadayoshi and sought to make them his own retainers. This was revealed after members of the Mukawa group opposed to his actions appealed directly to Ieyasu. Moreover, Yoshitsugu had a falling out with Hiraiwa Chikayoshi, the chief retainer of Tokugawa Yoshinao (the successor of Tadayoshi in Owari) who also had been appointed by Tokugawa Ieyasu (the first shōgun of the Edo bakufu). This in turn led to the discovery of improprieties. Consequently, Yoshitsugu, along with his second son, Nagamitsu, who was serving the Ikeda clan of the Himeji domain, were both ousted.
Yoshitsugu spent the remainder of his life in the village of Ikebe in the Tsuzuki District of Musashi Province, dying in 1616 at the age of sixty-nine. Nagamitsu, who was living with him in the village of Ikebe, died in 1620. His descendants served as hatamoto, or direct retainers, of the Edo bakufu.