Page "Emperor Tenji" Paragraph 4

As prince, Naka no Ōe played a crucial role in ending the near-total control the Soga clan had over the imperial family.

In 644, seeing the Soga continue to gain power, he conspired with Nakatomi no Kamatari and Soga no Kurayamada no Ishikawa no Maro to assassinate Soga no Iruka in what has come to be known as the Isshi Incident.

Although the assassination did not go exactly as planned, Iruka was killed, and his father and predecessor, Soga no Emishi, committed suicide soon after.

Following the Isshi Incident, Iruka's adherents dispersed largely without a fight, and Naka no Ōe was named heir apparent.

He also married the daughter of his ally Soga no Kurayamada, thus ensuring that a significant portion of the Soga clan's power was on his side.