During the Koryaku Coup in 1379, Yoriyasu colluded with Yoshimasa SHIBA; he advised Yoshimitsu to banish Yoriyuki HOSOKAWA, his political enemy and Yoriyuki was ousted from power.
康暦元年（1379年）の康暦の政変において斯波義将と共謀し、義満に進言して政敵の細川頼之を追放させた。