Isari Hisamichi served as a bushō during the Sengoku and Azuchi-Momoyama periods.
Hisamichi was born as the son of Isari Yoshikata. Yoshikata was the son of Isari Akiyoshi who, in turn, was the third son of Shiba Akitaka. Hisamichi was the third head of the Isari residence.
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. Hisamichi supported the main branch of the Shiba clan and defended the Isari residence. The Shiba clan, in the era of Shiba Akinao, was decimated by the Nanbu clan. Hisamichi’s father, Yoshikata, remained loyal to the main branch of the Shiba, but, after losing his lord, fled to Hanamaki and spent the remainder of his life in seclusion.
While residing in seclusion in Hanamaki, during the Keichō era (1596 to 1615), Hisamichi was engaged by Kita Nobuchika, a chief retainer of the Nanbu clan. In 1612, he became a retainer of Nanbu Masanao. Thereafter, the Isari clan continued to serve as retainers of the Morioka domain.