Kotetsu

Kotetsu is a kind and energetic child. He is full of passion for his job of maintaining the battle doll Yoriichi Type Zero, even though he has not yet mastered the repairs. This causes him much initial grief and fear, as should the doll break, no one but him is skilled enough to fix it. However, after meeting Tanjiro Kamado he realizes that he cannot give up. He is often very frank and blunt at times. This can be to his own detriment however, as he has no problems being blunt about the notoriously ill-tempered Hotaru Haganezuka who retaliates by assaulting the boy. Despite this, he means the best and tries his hardest to help those around him. While at times he seems insecure and weak-willed, as shown when he attempts to argue with Muichiro Tokito's harsh but true statements, Kotetsu can also be hot-headed and barbed-tongued. Without Muichiro to see him in the company of Tanjiro, he openly insulted the Hashira on multiple occasions, which shocked Tanjiro with his sharp contrast in demeanor. Despite initially bearing a grudge against the Mist Hashira, Kotetsu openly wept and repeatedly thanked Muichiro for saving him from a demon attack, even taking back his hatred and insults (which Muichiro did not even know about). He began begging Muichiro to save Kozo Kanamori and Hotaru Haganezuka, showing that he is open to changing his feelings towards people and being on better terms.

Kotetsu is a child of short stature, pale skin tone, and black hair. He wears a yellow striped yukata, a red vest on top of it, and a Hyottoko mask (with notable eyebrows and cheek prints) that fully conceals his face. However, it's later revealed that Kotetsu's actual face is similar to his mask, having the same wide eyes, bushy eyebrows, and rosy cheeks. The kanji for |Hyottoko}} is written on the back of his vest. File:Volume 13 Extra Page 01.png|Kotetsu's face under his mask.

Overview: Despite his young age, he has shown to be a skilled teacher and trainer, as shown when he asks Tanjiro to face Yoriichi Type Zero. Kotetsu also corrected the posture and mistakes that Tanjiro made and how he had survived this way, which indicates that Kotetsu has had some trouble with demons.