After that, Nagataka was attacked by his elder brother, Yoshishige SAGARA who was backed up by an influential person of the Sagara family, Yoriyoshi UEMURA, and Nagataka was driven to kill himself.
その後、一族の実力者上村頼興の後援を得た実兄の相良義滋に攻められて、自害に追い込まれた。