Ryoen entered into priesthood at Kofuku-ji Temple in 1189 following his father's will, and learned Dharmalogy of the Hosso Study from his master Shinen, who had just resigned from the position of betto (chief officer).
1189年（文治5年）に父の意向で出家し興福寺に入り、別当職を辞したばかりの信円に師事して法相教学を受けた。