Kaigaku (Demon)

Though outwardly brash, haughty, and arrogant, Kaigaku is in fact cowardly and selfish. Like many orphans who grew up with nothing, he resorted to doing any immoral or demeaning acts as a means to survive, like thievery and drinking from a puddle. As a transformed Demon Slayer and a member of the Upper Ranks, Kaigaku was an extremely powerful demon. This is supported by the fact that he had to receive a lot of Muzan Kibutsuji's blood for him to turn into a demon as users of Total Concentration Breathing are more resistant to the effects of the Demon King's blood. As a Thunder Breathing user turned Upper Rank demon, Kaigaku possesses tremendous movement speed and reflexes due to the Thunder Breathing swordsmanship style placing a heavy emphasis on swiftness and bursts of speed.[10] This, combined with assimilating a large amount of Muzan's blood, makes Kaigaku an extremely fast fighter. He's a demon holding the position as upper rank six.

Appearance: Kaigaku is a muscular young man of average height and short, spiky black hair, with two thick strands framing his face. four navy blue flame-like markings on both sides of his cheeks, emerald green irises (originally colored cyan) with black sclera, elongated canines resembling fangs, sickly pale skin, sharp blackened nails, and pointed ears. By becoming a member of the Twelve Kizuki and rising to the position of Upper Rank Six, his eyes are etched with the kanji of "Upper Rank" (上じょう弦げん, Jōgen?) on his right, and daiji of "Six" (陸ろく, Roku?) on his left. he is shown to be wearing his signature black kimono secured with a blue obi over a stylized version of his black Demon Slayer uniform that has yellow flame-like markings near the chest area and has it's collar unbuttoned. His forearms are seemingly wrapped in kyahan-like material. He also wears multiple necklaces on his neck and wrist with light-turquoise colored strings that hold together blue magatama-like pendants that were yellow in color when he was human.