Since there are some records claiming that in 749, during constructing the Great Buddha of Todai-ji Temple, the senior nun, travelled to the capital Kyoto, transmitted an oracle that Hachiman was cooperating with the great Buddha's construction, it is understood that Hachiman had become a syncretistic deity in the harmonization of Shinto and Buddhism from an early period.
東大寺の大仏を建造中の天平勝宝元年（749年）、宇佐八幡の禰宜の尼が上京して八幡神が大仏建造に協力しようと託宣したと伝えたと記録にあり、早くから仏教と習合していたことがわかる。