Hotaru Haganezuka is a swordsmith affiliated with the Demon Slayer Corps. Hotaru wears a sunflower-patterned haori and a large, woven hat with hanging floral wind chimes. His head is wrapped in a spotted cloth and his face is concealed by a Hyottoko mask (wooden festival mask), similar to Sakonji Urokodaki. During the Swordsmith Village Arc, he is seen with a more muscular build compared to his initial appearance. 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 5, 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 right 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 the people from the Swordsmith Village. 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 or by having others pin him down (one method being tickling his sides). It is later on shown that his skills and concentration on swords is so immense that he would lose clients due to his eccentric and asocial behavior and is actually happy that Tanjiro still trusts him in making his swords. His concentration also prevents him from paying any attention to his surroundings when forging a decent blade, even when a Demon was attacking him.