He's a mercenary - apparently a very expensive one - hired by a faction within Hingashi that wants the whole country closed to foreigners, and was hired to help hold the residents of Kugane Castle and various foreign merchants hostage as leverage for closing the only port open to outside trade. Ultimately, his wages are unable to be met (due to our quick-footed thievery), and he abandons his employer after our fight with him concludes.

(also technically he has no Eorzean context, because he's Hingashan and thus Othardian, but that's just being pedantic).