According to "Nigatsudo engi" (Karmic origins of the Nigatsudo), Jicchu kasho, the disciple of Ryoben Sojo who was the kaisan (a founder of temple as the first chief priest) of Todai-ji Temple in 751, went into Tenkai (Tosotsuten (The fourth of six heavens in the world of desire)), where tennin (heavenly beings) live, in the heart of Mt. Kasagi and saw the tennin did the keka for Eleven-faced Kannon in Jonen Kannonin (the hall with kannon statue that is thought to be placed in Tosotsuten (Heaven)) and wished for the keka to be done also in this (the lower) world.
「二月堂縁起」によると、天平勝宝3年（751年）東大寺の開山、良弁僧正（ろうべそうじょう）の弟子の実忠和尚（じっちゅうかしょう）が笠置山の山奥で、天人の住む天界（兜率天　とそつてん）に至り、そこにある常念観音院で天人たちが十一面観音の悔過を行ずるのを見て、これを下界でも行ないたいと願った。