Furthermore, while he copied lots of Buddhist scriptures brought into Japan, he began to feel the need to study the essence of Tendai Doctrine behind Nanto rokushu and through the Wake clan whom he was familiar with, he pleaded Emperor Kanmu to send him as ryugakuso (foreign priest studying Buddhism) to study Tendai sect and bring Buddhist scriptures to Japan.
さらにそれまで日本に招来された大量の仏典を書写し研究する中で、南都六宗の背景にある天台教義の真髄を学ぶ必要を感じ始め、親交のあった和気氏を通じて桓武天皇に天台宗の学習ならびに経典の招来のための唐へ留学僧の派遣を願い出た。