The close relationship between Supreme Order Prince SAIONJI and Kojuro was due to the following facts: since his adoptive father Buheita NAKAGAWA and Rokuzaemon NAKAGAWA served on active duty for Kinmochi SAIONJI in the Boshin Civil War, the Saionji family and the Nakagawa family had a master-subordinate relationship; and his uncle Kenjiro NAKAGAWA enjoyed a close association with Kinmochi SAIONJI since the initial year of the Meiji Period to the Taisho Period.
中川の養父・中川武平太、実父・中川禄左衛門が戊辰戦争で西園寺に従軍して以来、西園寺と中川家が主従関係にあったこと、叔父・中川謙二郎が明治初年から大正期にかけて西園寺公望と親しくしていたことが西園寺公と小十郎の親密な関係の礎となった。