Though Nagakata's father was Yoshitoshi YAMAZAKI who was a kotaiyoriai onreishu (a special high rank among a family status of samurai warriors), Nagakata's mother was a daughter of Nagakuni KURODA and, therefore, Nagakata was adopted as a son adopted at the deathbed.
父は交代寄合御礼衆の山崎義俊であったものの、母は黒田長邦の娘であったため、末期養子に迎えられた。