Sadaharu had excellent diplomatic skills and, among other successes, is said to have brokered peace between the shoguns of the day, Yoshiharu ASHIKAGA and Harumoto HOSOKAWA.
外交手腕に優れ、時の将軍・足利義晴と細川晴元の和睦を仲介したりなど、多くの功績を立てたと言われている。