The head of the Matsui family can be described as being essentially a daimyo-class lord of the Yatsushiro branch domain who had a stipend of 30,000 koku in Higo Province during his time as a retainer to the Hosokawa family.
松井家は細川家臣でありながら、実質上の肥後八代支藩3万石の大名格藩主であったともいえる。