Ōishi Yoshio

Ōishi Yoshio (大石 良雄, 24 April 1659 – 20 March 1703) was the chamberlain (karō) of the Akō Domain in Harima Province (now Hyōgo Prefecture), Japan (1679 - 1701).

He served daimyō Asano Naganori as the head chamberlain (hittōgarō (筆頭家老)) for the Akō estate, supervising the daily running of the castle and the samurai.

He then began a careful plot to kill Lord Kira, but to throw off suspicion, first spent time (and money) in the geisha houses of Kyoto.

This type of ruse is referred to as hiru andon (昼行灯, daylight lantern) – appearing to be serving no useful purposes, and this term is frequently applied to Ōishi.

After Ōishi dispatched Terasaka Kichiemon to inform Asano's widow Yōzeiin of the deed, he and the remaining 45 rōnin went to Sengaku-ji in Shinagawa where Naganori was buried and there they were arrested.