His paternal grandmother Imperial Princess Koshi was the maternal sister of Emperor Heizei and Emperor Saga, and he himself was also one of the influential heirs to the imperial throne.
父方の祖母・高志内親王は、平城天皇・嵯峨天皇両天皇の同母兄弟であり、王自身も皇位継承の有力な資格者の1人であった。