In-Su is a very straightforward, no-nonsense man, ever since he was a child he has always make sure that everything is in order and strictly follows rules. He became a detective when he was just 22 and has been known to be cold with limited tolerance for even the smallest mistakes ever since, which is why he tends to scare off newbies. Likes to either smoke or drink when he's off-duty. The highlight of his work is when the culprits or suspects are intelligent enough to be a challenge to him.