When the War of Zenshu UESUGI broke out in 1416, Iezumi's father Mitsuzumi IWAMATSU took the side of Iezumi's maternal grandfather (opinions are divided on this relationship) Zenshu (Ujinori) UESUGI, and in 1417, Iezumi's father was hunted down and executed by the Muromachi bakufu (Japanese feudal government headed by a shogun).
父の岩松満純は応永23年（1416年）に外祖父（異説あり）の上杉禅秀の乱で上杉禅秀（氏憲）に味方し、応永24年（1417年）に室町幕府による追討を受けて処刑されている。