Although Tsunemasa had taken over the post of Hitto karo of the Toyooka clan from his father Tsuneaki, and he had gotten married to Marihime, the daughter of the former lord of the domain Takasumi KYOGOKU, the confrontation with the present lord of the domain Takanaga KYOGOKU had become very serious regarding the reformation of the domain duties, and so in 1747 he resigned his position as karo and left the Toyooka domain.
父毎明から豊岡藩筆頭家老職を受け継ぎ、また前藩主京極高住の娘万里姫を妻に迎えたが、当代藩主・京極高永とは藩政改革を巡って対立を深め、延享4年（1747年）に家老を辞して豊岡藩を去ることになる。