He appears to be a collected and quiet person as he often speaks when he really needs to convey his thoughts. In fact, Seyoung is shy by nature but has a habit of saying things too blunt. His manner of speaking often makes people misinterpret what he means. People are often caught off guard by his sharp gaze and also, he has a habit to sneak on someone. His eyes catch onto minute details; his actions are likely never wasted. Whenever a problem occurs, he acts upon the most efficient solution available to him. He has habits such as mumbling the words with quiet voice or writing down anything he deems interesting.

Though he appears composed, Seyoung is counted as a childish, pigheaded and gets irritated a lot, especially when he's way too exhausted. When he's angry over something, he's definitely going to shout out row of unnice words. But as he grew up, he decides to conceal her annoyance by either smiling or laughing, or even plastering an ignorant look.

He may look as an indolent, but in fact, he always prefers every environment around him and himself to be spotlessly clean. Therefore his room seems unsoiled, to the point where he diligently clean it once in awhile.