He gets jealous quite easily and often especially when it comes his own pride and intelligence. He lis prone to moodswings, first appearing confident and cold, then suddenly depressed, then immediately switching to excitement, to the point of laughing uncontrollably.  He isn't known to have many friends, with the exception of his raccoon, Karl, who he considers his greatest and most trustworthy pal, and Ranpo Edogawa, of the Armed Detective Agency, who he desparately wants to outsmart.