He was the first son of Harukazu MITSUBUCHI, his half brother was Yusai HOSOKAWA (adopted son of Mototsune HOSOKAWA, hankoku shugo [military governor in charge of the half area of the Province] of Izumi Province.)
三淵晴員の長男で異母弟には細川幽斎（伯父の和泉国半国守護細川元常養子）がいる。