Lifespan: Ōnin 1 (1467) to 8/5 of Eishō 9 (1512)
Title: Junior Fifth Rank (Upper Grade); Governor of Izu
Father: Akazawa Tomotsune
Siblings: Nagatsune (brother-in-law)
Akazawa Masatsune served as a bushō in the early Sengoku period.
In 1467, Masatsune was born as the eldest son to Akazawa Tomotsune, a retainer of the main branch of the Hosokawa known as the Keichō-Hosokawa family.
He served Ashikaga Yoshimasa, the eighth shōgun. After Tomotsune moved to Kyōto, Masatsune remained in Shiozaki Castle in Shinano Province. In 1485, he was awarded the Court titles of Junior Fifth Rank (Upper) and Governor of Izu. In 1507, Tomotsune died in an internal conflict in the Keichō-Hosokawa clan. At this time, Masatsune defended Onoe and Takaya castles, but these fell in 1508, and he returned to Shinano the following year. In 1512, he was killed in the Iinuma residence.