Although Ishikawamaro was a member of the Soga clan, he was hostile to the head family of the Soga clan, including Emishi and Iruka, and he conspired with anti-Soga forces, including Naka no Oe no Oji (a.k.a. Katsuragi no Miko, who later became Emperor Tenchi) and FUJIWARA no Kamatari, to support the Isshi no Hen (the Murder in the Year of Isshi or the assassination of SOGA no Iruka), which took place in 645.
石川麻呂は蘇我氏の一族でありながら蝦夷、入鹿らの蘇我氏本宗家とは敵対しており、中大兄皇子（葛城皇子、後の天智天皇）、藤原鎌足らの反蘇我勢力と共謀して、皇極天皇4年（645年）に起きた乙巳の変（蘇我入鹿暗殺事件）に加担した。