Taking into consideration the descriptions including engi and Izuna-koshiki, it can be assumed that a systematic Izuna belief was already formed in the beginning of the Middle Ages.
先に見た縁起や講式等の記述等と併せて考えるならば、中世初期にはかなり体系的な飯縄信仰像が形成されていたと考えられよう。