Korekiyo is voiced by Todd Haberkorn

Korekiyo is a tall, slim student with rather pale skin and long black hair. His hair is stated to follow an archaic image of beauty and it "puts his female colleagues to shame". He has narrowed yellow eyes, and his mouth is covered by a black mask, covering his mouth and neck, with a zipper where his mouth would be, giving him an unsettling and mysterious appearance. He wears the mask wherever he goes, no matter where he goes, and he even owns different masks for eating, showering, and other daily activities.

Korekiyo is an aloof and somewhat creepy person, but he is also very cool-headed and intelligent. He has the experience of having met to a huge variety of human beings for his cultural anthropology research and because of that, he can keep himself composed even under the confinement circumstances and believes in facing things with calm and rational approach rather than an emotional one.[7] He has a vast knowledge of different cultures and ponders different subjects in deep and complex manner, with him occasionally starting lengthy anthropology speeches even though nobody asked. He is greatly interested in topics he does not necessarily agree with as well, as he states he does not believe in any gods, but he finds them interesting from the point of view of studying the human nature and cultures. However, he does believe in ghosts and souls, and has a strong interest in communication with the dead and death in general.