He was selected as a Buddhist priest to study overseas at the age of 25, went to Tang Dynasty China and studied both Yuishiki doctrine (theory that all existence is subjective and nothing exists outside of the mind) and Hokke doctrine for 31 years there. In China, he was selected the second highest in the Hundred High Seat, revised some 40 rolls of sutra-related documents including "Hokekyo-gisho" and "Yuishiki-sengi," and brought back to Japan about 500 rolls of key passages from Buddhist sutra he had copied by hand. The Imperial Court gave 30 disciples to him in reward for his great achievements. Back in Japan, when he was asked a difficult question about the doctrine by Myoitsu of Todai-ji Temple, he could not answer. Gyoga was severely abused by Myoitsu, but it is said that he could not answer because he forgot Japanese during his long stay in China. Gyoga, however, felt ashamed of this incident and dedicated himself to studying. He was assigned Shosozu (junior secondary prelate) in 784 and Daisozu (the upper Buddhist priests in the second highest position) in 796.
The above information is briefly introduced in the obituary section of "Ruiju Kokushi" (Assorted National History).