Jumin is a quiet, serious, and cautious man who, as the oldest, acts as the logical and pragmatic voice of the group. Despite this, he frequently jokes with the other members, even if they berate him for it and don't understand his strange and convoluted sense of humor. His general cadence will give off that of a child's, often being innocently unaware of things outside of business dealings. He is a workaholic and often works his assistant, Jaehee, to the bone. Jumin disregards others' opinions of him, so he lives his life however he wishes, which on the surface portrays him as unsympathetic and haughty. Even so, he cares deeply for the other members of the RFA, and does not hesitate to use his money and authority to help any of them when necessary. His best friend is V, whom he trusts unconditionally.

During Jumin's Route, it is revealed that he is not so cold and unfeeling as he portrays himself; instead, he is a man who feels far too much but, for the sake of efficiency, he pushes his feelings down, repressing them and using work and his cat to distract himself. This has led to Jumin to develop severe, crippling loneliness and he does not know how to work through it, viewing himself as a 'monster', thinking himself to be an ugly creature because of how lonely and paranoid he is. To cope, he projected this loneliness onto his cat, Elizabeth the 3rd, and is overcome with despair when he admits that he knows their "friendship" is a lie--that a pet cannot understand him at the level of another human being, and never will.

If the protagonist sides with him and enters his route, Jumin becomes alarmingly possessive at first. Because of previously being forced to put on a front and repress his emotions, their friendship and eventual relationship is rocky as he struggles with the intensity of his feelings coupled with his internal fears of being abandoned and rejected. He even goes so far as to trap her in his apartment, much to the outrage of the other RFA members. However, with the protagonist's help and the support of his friends, Jumin overcomes all his fear and anxiety and "untangles" his emotions that were knotted for many years.

Voice Quality: Medium-deep pitched. Quiet and serious, but can portray a dry sense of humor.

Voice Reference: https://www.youtube.com/watch?v=p8ZYptQ2OgA