Tamura Muneaki declined to adopt him as heir as expected, and although the young Akiyoshi was sent to Ichinoseki, he was not given any official title or duties.

The sudden death of Date Narimune without an heir placed Sendai Domain in a very precarious position vis-a-vis the Tokugawa shogunate.

He was proclaimed 11th Date daimyō of Sendai, and was received in formal audience by Shōgun Tokugawa Ienari three months later.

He was granted the Court rank of Junior Fourth, Lower Grade and courtesy title of Mutsu-no-kami.

His death reopened the succession issue within Sendai Domain, as his son and heir was still a child.