Korekiyo is an aloof and somewhat creepy person, but he is also very cool-headed and intelligent.[7] 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.[8] 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.

Korekiyo usually speaks in calm and polite manner, but he nevertheless comes across rather off and makes others uncomfortable due to his strange and sometimes morbid thinking. While he is most of the time very collected, with his voice staying the same tone, he occasionally gets very excited about some topics and his voice turns notably more high-pitched.