In 887, Emperor Koko was on his deathbed, and Mototsune proposed to make the Emperor's seventh son, Prince Sadami (who subsequently became Emperor Uda) heir to the throne.
仁和3年（887年）、光孝天皇が重篤に陥ると、基経は第7皇子の宇多天皇を皇嗣に推挙した。