Koyasan which is located in Wakayama, was the place where Kukai set up the headquarters of the Kōyasan Shingon sect of Japanese Buddhism. Sometani commented that he was very happy to be able to hold such an event at this sacred place and felt goosebumps for the first time when doing a completion press conference because he was so moved by the excitement of the spiritual energy there. Although Sometani and Abe are in the same movie, they had no scenes together due to the different time settings where their characters existed. Nonetheless, the two of them were full or praises for each other as Sometani said that he was touched by Abe's acting while the latter complimented Sometani's great performance as Kukai despite his young age.
The set used for the filming was built on a place which was 8 times bigger than Tokyo Dome and Sometani revealed that they were not just mere fronts but actual buildings where a lot of detail was paid to in making the set look as realistic as possible. As such, he was really happy to be able to film the movie in such a place. Abe also echoed his view about the myriad of colours on the set which made it feel really fantastical and dreamy. When asked about if his impression of Kukai had changed after acting in this movie, Sometani said that the Kukai in this movie is humourous and very approachable which may be different from how people usually perceive him to be.