Masakazu's father Masatsugu KOBORI, who served Nagamasa AZAI and Hideyoshi TOYOTOMI, was given a territory of 14,460 koku based on the Bitchu Matsuyama Domain after the Battle of Sekigahara for taking sides with the East squad successfully in it.
政一の父・小堀正次は浅井長政、豊臣秀吉に仕え、関ヶ原の戦いでは東軍に与して功を挙げたことから、戦後に備中松山藩を中心として1万4460石の所領を与えられた。