The Ishikawa clan of Mutsu Province including Akimitsu ISHIKAWA in the Mutsu was from a different family line; they were the descendants of the Yorichika line (Yamato-Genji [the Minamoto clan of Yamato Province) of Seiwa-Genji (the Minamoto clan from the descendants of Emperor Seiwa).
陸奥の石川昭光などの石川氏は別流で、清和源氏頼親流（大和源氏）石川氏族。