Y'know when you're a really good samurai, but not quite good enough to establish your own domain? That was the Matsui clan of Yatsushiro, who cleaved onto the Tokugawa clan and managed to survive (useful to the shogun as it provided a check against the rebellious Satsuma). Judging by the uniform, it must not have been an easy gig. There is an exhibition of their stuff now at the 八代市立博物館. William
https://kumanichi.com/articles/248823