Shinjuro strongly resembles his sons, Kyojuro Rengoku and Senjuro Rengoku, possessing unruly orange hair that flares out around his face, becoming redder near the ends above his ears, that he wears messily tied back behind his head. Shinjuro is a very short-tempered man, especially when regarding the Demon Slayer Corps and his son, Kyojuro, with the mention of either causing him to grow furious. He appears to be abusive, harshly insulting his children.