Shugo was in name only in the generation of Mototsune HOSOKAWA, the son of Motoari, and he and his brother Harukazu MITSUBUCHI became trusted vassals of the Shogun, Yoshiharu ASHIKAGA.
子・細川元常の代には守護とは名ばかりで、弟の三淵晴員とともに将軍足利義晴の近臣となっていた。