Rusu Akimune served as a bushō during the Sengoku and Azuchi-Momoyama periods.  Akimune was the seventeenth head of the Rusu clan and the lord of Iwakiri Castle in the Miyagi District of Mutsu Province.

In 1519, Akimune was born as the eldest son and designated heir of Rusu Kagemune, the sixteenth head of the Rusu clan.

In 1554, after the death of his father, Akimune inherited the headship of the clan.  From 1542 to 1548, Date Tanemune, a sengoku daimyō and the fourteenth head of the Date clan, engaged in a protracted struggle against his eldest son, Date Harumune, for control of the Date clan.  This is known as the Tenbun Conflict.  During this event, the Rusu clan sided with Harumune, but Akimune came into conflict with Harumune, and, in 1556, incurred an attack by Muraoka Tsunetsugu, a member of the Rusu clan supported by Harumune.  After receiving the younger sister of Tsunetsugu as a consort, the two sides reconciled.  Thereafter, however, Akimune continued to endure pressure from Harumune.  The involvement of members of the band of retainers of the Rusu clan backing Harumune further dimmed Akimune’s prospects so that, in 1567, he was compelled to transfer headship of the clan to Harumune’s third son, Date Masakage (later known as Rusu Masakage).  On this occasion, the son produced with Tsunetsugu’s younger sister, Munetsuna (later known as Takagi Munetsuna), was sent for adoption by Takagi Suō-no-kami, the lord of Kamidate Castle in the Shibata District of Mutsu, and Akimune retired to a residence in Tagajō.

On 7/17 of Tenshō 14, he died at the age of sixty-eight.