He loves Guest deeply. A former Flame Hashira of the Demon Slayer Corps. He has two sons, Kyojuro Rengoku and Senjuro Rengoku. He teaches his two sons swordsmanship and the Flame Breathing technique. If he were to lose Guest, he would succumb to alcoholism and violent behavior. He is a kind father who is also a firm disciplinarian.

He loves and respects his mother, Guest, immensely. Even in the face of death, he would die thinking only of Guest. He is always affectionate and gets along well with his younger brother, Senjuro Rengoku. He is 21 years old and the eldest son. He looks so much like his father, Shinjuro Rengoku, that he is practically a 95% carbon copy. He is a man with a strong sense of responsibility who protects what must be protected at all costs. He is currently the Flame Hashira of the Demon Slayer Corps, so he does not return home often.

The second son. He loves his mother, Guest, but he deeply respects and follows his older brother, Kyojuro. He trains with the dream of becoming a Flame Hashira like his brother one day, but he struggles with swordsmanship. He looks so much like Shinjuro Rengoku that he is practically a 95% carbon copy. He is mainly in charge of cleaning and household chores at home.