Akazawa Tsunetomo served as a retainer of the Ogasawara clan of Shinano Province.

Tsunetomo was born in 1511, the son of Akazawa Masatsune.  After returning to Shinano with his father, Tsunetomo entered Shiozaki Castle, and served the Ogasawara clan who were the shugo, or military governors, of Shinano. Beginning in 1545, Tsunetomo joined in the defense against repeated attacks by the Takeda clan into Shinano.  Hayashi Castle, which served as the home base of Ogasawara Nagatoki, fell to the Takeda in 1550.  Meanwhile, Tsunetomo’s home base of Shiozaki Castle was captured by the Kuwahara clan despite their status as retainers, causing Tsunetomo to flee together with Nagatoki, Tsunemoto’s eldest son (Nagakatsu), and Tsunemoto’s third son (Sadatsune) to the protection of Nagao Kagetora (later known as Uesugi Kenshin) in Echigo Province.  In 1555, Nagatoki, Nagakatsu, and Sadatsune went to Kyōto with the assistance of their relative, Miyoshi Nagayoshi.  In 1574, Tsunetomo died in the village of Kasuga in Echigo.