Karasuma is a strict but kind man, though he keeps a distance between himself and the students due to his status as an agent and professionalism. He is also extremely dense when when it comes to love. (What's more, in the anime it is said that one of his few weak points is being short for those things)
Although he comes off as aloof, he is not completely devoid of emotion and seems to express happiness very rarely; he is a good man and wants the best for his students.