However there were a few Princes eligible to succeed to the throne, many Princes were not able to become Emperors from early to Middle Heian period.
しかし、実際に皇位継承できる皇子はごく少数に限られ、平安前期から中期にかけて、皇位継承の道を閉ざされた皇族が多数発生することとなった。