According to "Mizu Kagami (The Water Mirror)", when Imperial Prince Osabe, the Crown Prince of Emperor Konin was deposed and a new crown prince was to be selected, Fujiwara no Momokawa recommended Imperial Prince Yamanobe, the first Prince of Emperor Koin, but Hamanari recommended Yamanobe's paternal half-brother, Imperial Prince Hieda whose mother (Princess Owari) was from a local ruling family because he was concerned about the fact that Imperial Prince Yamanobe's mother (TAKANO no Niigasa) was from an immigrant family (Yamatouji).
光仁天皇の皇太子であった他戸親王が廃され、新たな皇太子を選定する際、光仁天皇の第一皇子・山部親王を推す藤原百川に対し、浜成は山部の母（高野新笠）が渡来系氏族（和氏）の出身であることを問題視し、山部の異母弟で母（尾張女王）が皇族出身である薭田親王を推挙したとされる（『水鏡』）。