Actor Tak Sakaguchi broke one finger, one rib and four of his teeth during the 77 minute battle sequence.
The 77 minute sequence was shot in 2011. The project unfortunately sat unfinished for nine years. In 2018, through the crowdfunding site Campfire, the production raised 7,818,500 Yen to complete the film. Funding was used to shoot additional sequences to bookend the story, rerecording the audio, animating CGI for blood effects, and for marketing. The film was completed in 2020.
In the central 77 minute one shot one take sequence, the character of Musashi Miyamoto kills a total of 588 opponents, rather than the number of 400 used in the some of the marketing.
In the sequence labeled "7 years later..." it was actually filmed more than eight years after the previous scene.
The stunt team rehearsed for months in preparation for the canceled production of Kenkichi. Actor and stuntman Tak Sakaguchi proposed an idea to expand the initial ten minute one shot sequence into a lengthier feature, and kept the already prepared stunt team to train for eight months for the new idea.