The Akō Domain (赤穂藩 Akō Han) was a domain in feudal Japan. It was located in Harima Province and coincided with the present-day cities of Akō and Aioi and the town of Kamigōri in Hyōgo Prefecture. The domain had its headquarters at Akō Castle. Naganao's grandson Naganori was the daimyo of Akō at the time of his attempt to kill Kira Yoshinaka in Edo Castle in 1701. He was sentenced to commit suicide and his retainers became ronin. A group of them became famous as the Forty-seven ronin.