However, when Emperor Shijo suddenly died in 1242, Sadamichi sent a secret messenger to Kamakura for the Regent Yasutoki HOJO who was his brother-in-law and worked towards the ascension of Prince Kunihito.
だが、仁治3年（1242年）四条天皇が急死すると、定通は密使を鎌倉に派遣して義理の兄に当たる執権・北条泰時に邦仁王の天皇擁立を働きかけた。