Hotaru Haganezuka is a supporting character of Demon Slayer: Kimetsu no Yaiba. He is a swordsmith affiliated with the Demon Slayer Corps. Hotaru wears a sunflower-patterned haori and has his head wrapped in a spotted head scarf. Like the rest of the swordsmiths, his face is concealed by a Hyottoko mask (wooden festival mask) to conceal his identity. When traveling he wears a large, woven hat with hanging floral wind chimes on top of the head scarf. During the Swordsmith Village Arc, he is seen with a more muscular build compared to his initial appearance after he had been training in the mountains. Unmasked, Hotaru is revealed to have long, black hair coupled with sharp eyes and distinctly-shaped thick eyebrows. However upon being attacked by Upper Rank Five, Gyokko, Hotaru now possesses several deep scars and cuts from the Demon all over his body, including an X-shaped one on his face, and has now lost the use of his left eye. Hotaru is a rather hot-blooded individual. He seems to show very little care, if any, about anything besides the swords he creates. His passion for swords is so strong that he would be able to speak about them for long periods of time, a trait unique even among other swordsmiths. The same passion that gives him the enthusiasm and extreme dedication in creating swords is also the reason why he is easily enraged (usually in a comical fashion) towards swordsmen that break his creations, especially Tanjiro Kamado, no matter the circumstance. When angry, he usually calms himself down by eating mitarashi dango. Bystanders can subdue him by either pinning him down or tickling his sides, as demonstrated by Kozo Kanamori, after which he will fall limp. As Hotaru is socially inept in dealing with people, he is still unmarried. His intense and asocial behavior also causes other swordsmen to hate him and he lost a lot of clients because of this. Although he won't be honest about it, he is actually happy that Tanjiro still trusts him in making his swords. His concentration on sword making is so immense that it prevents him from paying any attention to his surroundings when forging a blade, even when a demon is attacking him and inflicting severe injuries on him. When the process of forging or refining is interrupted by taking the sword away, he feels the need to restart the whole process from scratch again. As a perfectionist, any small scratch on a blade that is irremovable hurts him immensely.