Kyojuro Rengoku was a major supporting character of Demon Slayer: Kimetsu no Yaiba and a major character in the Mugen Train Arc. He was a Demon Slayer of the Demon Slayer Corps and the late Flame Hashira. Kyojuro was a young adult of tall stature and muscular-athletic build. He had long bright yellow hair with red streaks akin to flames along with two shoulder-length bangs and two chin-length bangs on the side of his head, black forked eyebrows, and golden eyes that fade to red with white pupils. He was known to be charismatic and had an air of great optimism, having an enthusiastic smile plastered on his face nearly all the time. Kyojuro wore a paler brown version of the regular Demon Slayer uniform, which consisted of a brown gakuran jacket, a white belt around his waist and tattsuke-hakama pants. Over this, he wore a haori with a white-yellow gradient pattern and red flame-like ridges at the end that his father Shinjuro once worn and more than likely his father worn when they were the Flame Hashira respectively. Finally, he wore red kyahan with yellow flames erupting from the bottom-up, with pale brown tabi socks and a pair of white zōri with red straps. When he first joined the Demon Slayer Corps, he only wore the regular Demon Slayer uniform but as he rose up the ranks, Kyojuro started wearing a completely white haori before donning on his signature flame-patterned one. Kyojuro was greatly enthusiastic in regard to his duties as a Hashira, and often came across as cheerfully eccentric. He was amiable, pure of heart, and boasted extraordinary technique and swordsmanship stemming from strict practice and discipline. He was an honorable warrior who adhered to his code of morals and principles that was instilled into him by his mother at a young age; the most significant being his belief that those who were born strong have a duty to protect the weak. Kyojuro also loved his family immensely, displaying great respect and worry towards his father, Shinjuro Rengoku, despite him growing slowly more aggressive and apathetic towards Kyojuro. He was incredibly encouraging and optimistic towards his little brother, Senjuro Rengoku, believing in him and wishing him the best no matter what. This was further accentuated during his death where his final words for his father and his little brother were "take care of your body" and "follow your dreams no matter what". Kyojuro also believes that if someone lacks immense skill, their hard work towards their dreams and desire to help people doesn't count for nothing. Beneath his enthusiastic demeanor, Kyojuro was very logical and tactically intelligent, acting quickly and precisely in battle, especially when the lives of others are on the line. Kyojuro was also great in seeing talent in others, even in Nezuko Kamado, a demon which he wanted to kill beforehand, after seeing her risk her lives to fight and protect others. Though he was extremely optimistic, Kyojuro does sometimes have a sense of foreboding that those he believes in might die, especially his friends which he care deeply for. He, like most Demon Slayers, absolutely detests demons, usually because of their heinous deeds or because of their clashing morale values. Despite this, Kyojuro recognized and accepted Nezuko as a member of the Demon Slayer Corps after seeing her risk her life to protect innocents, showing that Kyojuro was capable of not letting his hatred for demons cloud his judgement.