Heiji is kind of a typical high school student. Given or not some of his unique quirks, for example, he is smarter than most kids his age. He has an amazing memory. Where most find a scary corpse and get squeamish, Heiji is the first to jump on it and decipher the cause of death or if he's even dead. Mysteries fascinate him like children watching an interesting video game. If a case emerges, you can bet Heiji will be there ready to explode every cell in his brain. He could be described as quite impulsive and sometimes even a little absent-minded. His father described Heiji like this: "He's like a little boy running on pure instinct." Like Kudo, Heiji's intelligence is unmistakable. With or without Kudo's help, he can interpret clues, predict motives, and reveal the culprit, all in a day's work. Complicated puzzles and strange clues are not safe from his deductions. With this intelligence the intelligent thinking process is its ability to create its own clues. Aware of many knowledge and facts, he can determine how long a body has been dead, what killed it, and (after a bit of sleuthing) how. He seems to lack a higher authority. When his father (mind you knowingly) punched Heiji to the ground, he belittled him and told him to go home because this case was none of his business. Instead Heiji rebelled and continued working on it despite his father's action. He also has a knack for calling his mother "old", and doesn't even properly address Mouri. Also, unlike Kudo, Heiji has more fiery blood. He is quick to lose his temper, quick to jump the gun, and quick to run wherever a clue leads him. Even though he manages to maintain his composure most of the time, he still reveals enough to be noteworthy. Hakuba actually scolded... halfway through the paper... he even mistook a 'nervous almost confession' for nervousness because 'they feel hungry'. When in reality their feelings are deeper and more intimate. Heiji is also unaware of his own feelings for her. There were a few moments when he wanted to confess it to her, but he was halfway there and changed the subject to something ridiculous in comparison. One thing you'll notice about Heiji every time you see him, and I mean every time, is the fact that he's wearing a beige baseball cap with a dark blue visor. On it is the acronym "SAX", his favorite baseball team. That said, baseball is his favorite sport and he actively follows it. You will almost never see him without his cap. The cap is also used as a tool. As during cases, if he throws his hat forward, where the bill becomes front and worn correctly, it means he is close to solving a case.