Otaka served Lord Naganori Asano of Ako first as a page, then as steward and magistrate. After Naganori committed hara-kiri, he changed his name to Shimbe Wakiya, went to Edo and spied on the household of Yoshinaka Kira, the enemy of his lord.
To obtain information, he became a friend of Itsuki Hagura, a tea ceremony master who frequented the Kira family. A haiku poet, he was a disciple of Kikaku Takarai and called himself Shiyo.
On the night of December 14, 1702, the 47 members of the Loyal League stormed the Kira residence and killed Kira. They committed hara-kiri by order of the Shogunate in February of the following year.