However, the succession to the throne wasn't Emperor Junna's intention (according to "Nihon Koki," on May 22, 806, when his father died, Prince Otomo asked to be removed from the Imperial Family, but he was dissuaded from resigning by the crown prince (Emperor Heizei)) and was worried that his son Prince Tsunesada, who lacked the support of court nobles, would become the crown prince of Emperor Nimmyo.
だが、その即位は天皇個人が望んだ皇位継承ではなく（『日本後紀』によれば、大同元年5月1日（806年5月22日）に大伴親王（当時）が父帝の死を機会に臣籍降下を願い出て皇太子（平城天皇）に慰留されている）、更に有力貴族の後ろ盾のいない息子恒貞親王が仁明天皇の皇太子になったことに不安を抱いていたと言う。