Emishi and Iruka became increasingly authoritarian, and the Soga clan usurped political power, using the 'purple crown' for their own purposes (the purple crown was used only for people of the highest rank such as emperors), and exterminating the Yamashirooenoo family (Uetsunomiya royal house) in 643.
さらに蝦夷・入鹿の専横は激しくなり、蘇我蝦夷が自ら国政を執り、紫の冠を私用したことや643年聖徳太子の子山背大兄王一族（上宮王家）を滅ぼしたことなど、蘇我氏が政治をほしいままにした。