Yoshihisa seems to have been proud of his family and the Shimazu clan, viewing Hideyaoshi as something of an upstart, and therefore choosing not to enter into corresponse with him.
義久は名族・島津氏の自尊心がかなり強かったらしく、秀吉のような成り上がり者を通信相手に選ばなかったといわれている。