According to "Kojiki," Iohara no kunimiyatsuko is a son of Hikosashikatawake no mikoto, a Prince of Emperor Koken, having Toshiba and Kunisaki clans in the same line of family.
『古事記』では孝霊天皇の皇子日子刺肩別命の子で利波氏・国前氏などと同系。