In the beginning of the Kamakura era, the King Enma Hall (Enmaō-dō) was established in Daigoji temple. During this period, Senyōmon-in was the sixth imperial princess in the line of Retired Emperor Goshirakawa-in and the head of a gogan sub-temple. She was deeply devoted to Shingon Esoteric Buddhism, but when and how did such devotion begin? The key is found in the incident of an ecstasy she experienced at the age of 17. The recounting of her own experience, a document that was thus far ignored by scholars, is an invaluable testimony that revolves around the mind and body of women in Medieval Japan. The paper sheds light on this story’s connection to the magical powers of an Esoteric practice known as Enmei shōkon sahō. I will argue that this event was the starting point for the construction of the King Enma Hall by Senyōmon-in and the monk Seigen.