Tsuneki Okajima was a samurai. One of the 47 Loyal Ronin of Ako. He was commonly called Yasoemon. He served Lord Naganori Asano of Ako as a senior page and concurrently as an accountant. He had unusual physical prowess and was a master of swordsmanship of the Sekiguchi school.
Tsuneki Okajima was born in 1672. He was a younger brother of Mototoki Hara. Was adopted by the Okajima family.
When Naganori was ordered by the Shogunate to commit hara-kiri in March, 1701, for his offense in the Shogun's castle, the Ako retainers were divided as to whether to turn over the Ako castle to the Shogunate as ordered, or defend it against Shogunate forces. Tsuneki who stood for defending the castle, wanted to get rid of Kurobe Ono, a chief retainer who was for obeying the Shogunate order. When Tsuneki went to Ono's residence, the latter refused to see him on the pretext of illness. Ono that night fled Ako out of fright. After the incident, Tsuneki changed his name to Takehachiro Kori and awaited the opportunity to avenge his lord.