Ei Hisatora governed Ei district in Satsuma province and by 1584 was serving as a counselor to Shimazu Yoshihisa. He fought in many notable battles, including the 1576 Battle of Takabaru, the 1578 Battle of Mimigawa, and the 1581 Battle of Minamata. He was wounded at the 1584 Battle of Okitanawate.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005
- Gregory Smits, Maritime Ryukyu, University of Hawaii Press (2019), 208.