The Setoguchi family was a distant relative of the Togo clan, the powerful local clan in Satsuma, and Togo was mentioned as Tobei SETOGUCHI or Setoguchi Hizen no kami in historical papers covering that period.
瀬戸口家は北薩の土豪薩摩東郷氏の遠戚にあたり、同時代の史料には瀬戸口藤兵衛または瀬戸口肥前守の名で登場することがある。