There is a theory that the Isshi no Hen was a coup caused by Karu no Miko (Emperor Kotoku), in which Naka no Oe no Oji (Naka no Oe no Miko) lost his position.
乙巳の変は軽皇子(孝徳天皇)のクーデターであり、中大兄皇子は地位を追われたという説。