Saburō Monma is a jujitsu master leading the Shinmei-Katsura school in the 1880s. He actively opposes Shogoro Yano's judo school due to conflicts over martial arts instruction opportunities with the Metropolitan Police Department. Monma organizes and participates in a confrontation against Yano at a waterfront location, where Yano defeats Monma and his students, throwing them into a river.

Following this defeat, Monma later challenges Sanshiro Sugata directly. During their official match, Sanshiro executes a specialized throwing technique called "Yamaarashi," throwing Monma with significant force. The impact causes Monma to strike his head against a wall, leading to his death. This fatal outcome occurs despite the match being a formal martial arts engagement.

Monma's death directly influences other characters. His daughter witnesses the fatal match and develops intense hatred toward Sanshiro. She later attempts to assassinate Sanshiro with a blade as revenge for her father's death, profoundly impacting Sanshiro's psychological state and forcing him to confront the consequences of his martial prowess. The original version of the film included more extensive scenes exploring Sanshiro's reaction to Monma's death and the daughter's vengeance, but approximately 17 minutes of footage were removed due to wartime censorship policies.

The character's name appears with variant spellings, including "Momma," clarified as a Japanese proper name. No information exists regarding Monma's background beyond his martial arts affiliation, family relationships, or appearances beyond the initial film narrative.