Lifespan: Eishō 3 (1506) (?) to Eiroku 9 (1566) (?)
Other Names: Isari gosho, or Prince Isari
Clan: Kōsuiji-Shiba → Isari
Father: Shiba Akitaka
Siblings: Shiba Tsuneaki, Shizukuishi Akisada, Akiyoshi
Isari Akiyoshi served as a bushi during the Sengoku period.
The Isari clan were an illegitimate branch of the Kōsuiji-Shiba clan who were members of the Ashikaga clan descended from the Kawachi-Genji, a branch of the Seiwa-Genji.
His father, Shiba Akitaka (a sengoku daimyō in Mutsu), ruled the village of Shizukuishi after garnering it from the Nanbu clan and became the lord of Shizukuishi Castle. When his second oldest brother, Shizukuishi Akisada, became the lord of Shizukuishi Castle, Akiyoshi kept a residence in Isari (near Morioka).
Owing to his being a member of the Ashikaga clan with the same founder as the Ashikaga shōgun family, he was respectfully called within the family as well as externally as Isari gosho, or Prince Isari.
His son was Isari Yoshikata (the father of Isari Hisamichi).