Kyojuro Rengoku

During their first meeting at the Ubuyashiki Estate, Kyojuro held a dislike for Tanjiro as he broke the Demon Slayer Corps' rule to protect his demon sister, and thus he insisted on killing Nezuko Kamado as well as seeking punishment for Tanjiro. However, as the story progresses, he begins to warm up to Tanjiro after meeting him again on the Infinite Train. The two hunters develop a mutual respect for each other as comrades in the Demon Slayer Corps, to the point where Kyojuro offers to make Tanjiro his Tsuguko. Tanjiro develops a strong admiration and closeness for Kyojuro, to the point where he calls him "Aniki" (big brother), showing their brotherly bond. Tanjiro is greatly impressed by Kyojuro's swordsmanship and his ability to smile despite adversity. Shortly before his death, Kyojuro entrusts his will to Tanjiro. Soon after, Kyojuro's tsuba is passed on to Tanjiro by his younger brother Senjuro.

Senjuro is Kyojuro's younger brother. Kyojuro loved and cared for him very much and mentored his younger brother in the Breath of Flame. According to Senjuro himself, he failed to master the Breath due to his lack of skill, so he gave up. However, Kyojuro was still proud of him. He was deeply saddened and depressed after learning of his brother's death.

Kyojuro's mother, who passed away from an illness when he was young. As shown in his memories of her, she was very strict towards him, yet loving and gentle towards him at the same time. She had a great influence on his overall philosophy, as she explained to him that he was born strong to protect the weak and to never use such a gift for selfish purposes. She loved Kyojuro deeply, as she tearfully expressed her gratitude for being blessed to have given birth to him as a child, a man born to be strong, kind, and gentle at the same time. Kyojuro cared deeply for her and loved her in return, as her words towards him gave him the final push to hold back Akazu in a final attempt to kill him despite his grievous wounds. In his final moments, Kyojuro saw his mother's spirit, who expressed that he had accomplished all the tasks she had set for him, and she was very proud of him, allowing him to die with a smile on his face.

The former Flame Pillar and Kyojuro's father. When Kyojuro was young, he and his brother trained under their father, who he described as a passionate man. After the death of his wife and his departure from the Demon Slayer Corps, their relationship became distant. Even after Kyojuro succeeded him as the Flame Pillar, Shinjuro paid no attention to it. After Kyojuro's death, Shinjuro insulted his son in a drunken stupor and seemed unconcerned about his passing. Kyojuro, on the other hand, never stopped caring for his father even after he became distant, and his final message was for him to take care of himself and his body. Upon hearing this, Shinjuro regretted his harsh words and mourned his deceased son. During the final battle against Muzan, Shinjuro joined the Demon Slayers alongside Tengen Uzui as the last line of defense to protect Kiriya Ubuyashiki, vowing not to dishonor the Rengoku Family or Kyojuro's memory.

The Pillars are the nine most powerful swordsmen among the Demon Slayers, supported by the Demon Slayers. Each Pillar has a unique breathing style, which they perfect and develop through extreme training. Behind this group is the leader of the Demon Slayers, Kagaya Ubuyashiki himself.

The Pillars are constantly looking for a Tsuguko (successor) to take their place after their death or retirement. Each Pillar is assigned to a specific region that they are charged with protecting.

They must also gather information about demons and improve their sword skills. To become a Tsuguko, you must either apply and the Pillars will approve you, or they will find you and take you for training. Also, the same breathing styles as the Pillar can help in choosing a successor, but they can still take a person with a different style. Joining In order to become one of the Pillars, a Demon Slayer must be one of the strongest fighters in the entire Demon Slayer Corps. There are two known methods to prove one's worthy of becoming a Pillar; the first method is for the swordsman to kill at least 50 demons; the second method is for one to kill one of the Twelve Moon Demons, the 12 strongest of all demons that serve directly under Muzan Kibutsuji.

The effort required to achieve any of these methods requires nearly five years of training, although talented individuals may only need two years or so.

Kyojuro Rengoku was born into the family of the Flame Pillar Shinjuro Rengoku.

As children, Kyojuro and his younger brother Senjuro were trained by their father in the art of swordsmanship so that they could follow in his footsteps and become demon hunters. At an unknown time when Kyojuro was still young, his mother Ruka gave him final instructions to protect the weak whenever possible and not to use his power for selfish purposes. After Ruka's death, Kyojuro's father began drinking and soon resigned as the Flame Pillar and stopped training his sons.

Despite this, Kyojuro, using the records of breathing techniques, mastered the flame breathing on his own and became a skilled swordsman. After this, he achieved the rank of Flame Pillar, like his father and their ancestors.

Kyojuro is a tall, strong-built young man. His most striking feature is his bright yellow hair with long strands that turn red in places. He also has thick, forked eyebrows and wide-open eyes.

Kyojuro wears a lighter, brown version of the normal Demon Slayer uniform. Over the uniform, he wears a cloak with a flame-like pattern and protrusions on the hem, which was once worn by his father Shinjuro and most likely his ancestors. On his feet, Kyojuro wears red tabi socks with yellow flames erupting from the bottom up, with a pair of white zōri with red straps. Kyojuro is a kind and honest man. He is quite eccentric, and tends to let his emotions run wild. However, Kyojuro has an unwavering optimism and tremendous fortitude, instilled in him by his mother at a young age, which helps him not only find strength in himself in difficult situations, but also support those around him.

Kyojuro is very enthusiastic about his duties as a Pillar and Demon Slayer. His worldview is based on the idea that the strong must protect the weak, instilled in him by his mother as a child. From his father, he inherited the discipline and determination he had gained through training.

Kyojuro is a kind and honest man. He is quite eccentric, and tends to let his emotions run wild. However, Kyojuro has an unwavering optimism and tremendous fortitude, instilled in him by his mother at a young age, which helps him not only find strength in himself in difficult situations, but also support those around him.

Kyojuro is very enthusiastic about his duties as a Pillar and Demon Slayer. His worldview is based on the idea that the strong must protect the weak, instilled in him by his mother as a child. From his father, he inherited the discipline and determination he had gained through training.