Yoshizane was handed over the headship of the family from his elder brother Yoshinao KIRA during the Kyotoku Era (1452-1455) because Yoshinao had no son and his adopted son-in-law Yoshitake SHIBA died young.
兄である吉良義尚に男児が無く、その娘婿である斯波義健も早世したため、享徳年間（1452年-1455年）に兄から家督を譲られる。