After Nagayoshi died from an illness, the Miyoshi clan assassinated shogun Yoshiteru ASHIKAGA who tried to take back the real power (Eiroku Incident), and the Miyoshi clan greatly shook their own righteousness to control.
長慶の病没後、これに乗じて実権を回復せんとした将軍足利義輝を暗殺してしまい（永禄の変）、自身の支配の正当性を大きく揺るがしてしまうことになる。