Kyoujurou is a major supporting character of Demon Slayer: Kimetsu no Yaiba and a major character in the Mugen Train Arc. He is a Demon Slayer of the Demon Slayer Corps and the former Flame Hashira.
Kyoujurou was a young adult of tall stature and athletic build. He is known have an air of great optimism about him, having an enthusiastic smile plastered on his face nearly all the time. 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.
Kyoujurou 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 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.
Kyoujurou 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.
Kyoujurou also loved his family immensely, displaying great respect and worry towards his father, Shinjurou Rengoku, despite him growing slowly more aggressive and apathetic towards Kyoujurou. He is incredibly encouraging and optimistic towards his little brother, Senjurou Rengoku, believing in him and wishing him the best no matter what. This is 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”. Kyoujurou 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, Kyoujurou is very logical and tactically intelligent, acting quickly and precisely in battle, especially when the lives of others are on the line. Kyoujurou also is great in seeing talent in others, even in Nezuko, a Demon which he wanted to kill beforehand after seeing her risk her lives to fight Demons. Though he is extremely optimistic, Kyoujurou does sometimes have a sense of foreboding that those he believes in might die, especially his friends which he care deeply for. Lastly, he, like most Demon Slayers, absolutely detest Demons, usually because of their heinous deeds or because of their clashing morale values.
Rengoku loses his life after a fatal blow from the Upper Moon Three, Akaza, during the Infinity Train Arc.
Master Swordsman: As he was a Hashira of the Demon Slayer Corps, Kyoujurou was one of the most powerful and skilled swordsmen in the entire organization. His mastery of the blade is best showcased during his battle with Akaza, in which he is able to hold his own against the Upper Rank even when gravely injured.
Flame Breathing (炎ほのおの呼こ吸きゅう Honō no kokyū): Taught to him by the previous Flame Hashira, Shinjurou Rengoku, and later mastered by reading the instruction books left behind by previous Flame Hashira in the Rengoku Family, Kyoujurou became extremely proficient in fighting with this Breathing Style, being able to go toe-to-toe with the former Lower Rank 2, Hairo and later Upper Rank 3, Akaza.
First Form: Unknowing Fire (壱いちノ型かた 不知火しらぬい Ichi no kata: Shiranui) - The user charges towards their opponent at high speed and decapitates them in one slash. Second Form: Rising Scorching Sun (弐にノ型かた 昇のぼり炎えん天てん Ni no kata: Nobori En Ten) - The user releases an arching slash attack upwards. Third Form: Blazing Universe (参さんノ型かた 氣き炎えん万ばん象じょう San no kata: Kien Banjō) - The user swings their blade downwards in an arc. Fourth Form: Blooming Flame Undulation (肆しノ型かた 盛せい炎えんのうねり Shi no kata: Sei En no Uneri) - The user swings their blade in a circular motion that can defend them from all incoming attacks or decapitate multiple enemies at once. Fifth Form: Flame Tiger (伍ごノ型かた 炎えん虎こ Go no kata: Enko) - The user unleashes a powerful series of sword slashes that seemingly takes the form of a rampaging tiger engulfed in flames that charges towards the enemy at blinding speeds. Ninth Form: Rengoku (玖くノ型かた 煉れん獄ごく Ku no kata: Rengoku) - A devastating dashing slash that the user initiates from a high stance, the technique had enough power to carve a deep impression that burnt the ground where it was unleashed.
Standard Nichirin Katana: Kyoujurou carries a standard sized and shaped katana made from Nichirin that is a deep shade of reddish-orange in color with the words Destroy Demons (惡あっ鬼き滅めっ殺さつ Akki Messatsu) engraved on the side. There is also a noticeable flame pattern on each side of his katana with a white handle. Kyoujurou’s katana’s hilt is shaped like a flame with a red core and golden border. He also carries a standard sword sheathe that is white and grey in color.