Akira Kurosawa begged Toho to buy the rights for him to make this movie before the book was even released. Producer Nobuyoshi Morita told him they could not buy the rights until the book was officially published. By his own admission, Kurosawa stalked book stores until he finally found a copy, which he bought and read immediately.
The book "Sanshiro Sugata," from which the movie was based, was written by Tsuneo Tomita who at the time of the book release was a 38 year old judo master turned novelist. The Sanshiro character was sculpted around Tsueno's teacher and celebrated judo expert Shiro Saigo (1866-1922).
The climactic fight scene was originally planned to be filmed on a staged set with painted clouds and large wind fans. Akira Kurosawa, unhappy with the look, got permission from the studio for three more outdoor location days. Day three delivered the huge windstorm used in the final footage.
When asked about his experience filming his debut movie, Akira Kurosawa said "I simply enjoyed it. I went to sleep each night looking forward eagerly to the next day's shooting, and there was absolutely nothing painful in the experience... the whole task was carried out with a feeling of ease."
Excited about his prospects at filming the movie, Akira Kurosawa visited Toho producer Nobuyoshi Morita in the middle of the night immediately after reading it to beg him to buy the rights. Morita agreed to send someone out the next day.
Cinematographer Akira Mimura recollected in his diary the outdoor scene of Yano fighting the jujitsu men by the riverside, claiming near zero temperatures forced the men thrown into the river to one by one be immediately pulled out of the water and driven to the hotel to warm up.
The Information Section of the Japanese Navy, just after the success of this movie, approached Akira Kurosawa about making a film focusing on Zero fighter pilots. Due to budget issues at this stage in the war, he instead made Ichiban utsukushiku (1944).