After his retirement, Tadaoki HOSOKAWA, the father of the lord Tadatoshi HOSOKAWA, resided in the Yatsushiro-jo Castle; since the castle functioned as the barrier that prevented the invasion of the Shimazu clan, it was regarded as an exception of the Ikkoku Ichijo Law (according to it, one province can keep only one castle); in 1646, Okinaga MATSUI was ordered to retain this castle, and from then on, the Matsuki clan served as a keeper of Yatsushiro-jo Castle.
藩主・細川忠利の父である忠興が隠居城とした肥後八代城は薩摩の島津氏に対する押さえの役割を持ち、特に一国一城令の例外とされていたが、正保3年（1646年）には興長が八代城を預かることになり、以後代々松井家が八代城代を務めた。