Sasebo Isamu served as a bushō during the Sengoku period.  He was the lord of Sasebo Castle in Hizen Province.

Isamu had landholdings in Sasebo and adopted the Sasebo surname.  He built Sasebo Castle.  On 11/2 of Meiō 7 (1498), Isamu’s older brother, Matsura Masashi, the fifteenth head of the Aikōnoura-Matsura clan based at Daichian Castle, was attacked by Matsura Hirosada.  During this event, Isamu declined to go to the aid of his brother, remaining silent.  It is surmised that is because Hirosada’s adopted son, Matsura Okinobu, was the brother of Isamu’s wife.

Isamu died in 1528.