Kokushibo

Kaigaku was a young man with black hair and turquoise eyes. When he became a demon, he gained black, flame-like markings on his face, fangs, and pale skin.

Kaigaku1 As an Upper Moon, he acquired kanji on both eyes. He typically wears a black kimono with a blue sash over his demon hunter uniform, which has yellow markings.

Personality Kaigaku is extremely proud, to the point that he will serve anyone who recognizes his strength. He is highly intelligent, using his breathing technique almost flawlessly. His ingenuity was only enhanced by his demonic transformation, as he used the special power of his blood to enhance his breathing. He hates weak people; when Kaigaku was Zenitsu's apprentice, he clearly saw him as weak, which is why he harbored hatred for him.

As a demon, Kokushibo is a pale-skinned, tall, and muscular man with long, spiky black hair with red tips, tied back in a ponytail. His most notable feature is the three pairs of eyes on his face, each with yellow irises and red sclerae, each with a black, straight slit extending from each iris. His middle set of eyes bears the kanji for "Highest Rank (上じょう弦げん, Jōgen?)" and "One (壱いち, Ichi?)". Kokushibo also has red, flame-like markings on the upper left side of his forehead and the lower right side of his chin. Kokushibo wears a purple and black nagagi kimono shaped like a beehive and a black umanori-style hakama with a white uwa obi. He wears a flesh sword with eyes in the space between the tsuka tsuka ito. It is later revealed that the tsuba and blade have eyes and veins. He is the most powerful demon, second in strength only to the demon king himself—Kibutsuji Muzan.