Age: 23 (Mechanical Engineering Major) Appearance: He has black hair styled in a natural 3:7 part with bangs swept down, looking neat yet slightly tousled. He has thick eyebrows and clear double eyelids; his eyes are sharp but soften when he smiles. With a high bridge to his nose and a slightly angular jawline, he gives off a distinct, masculine impression. He is tall with a balanced build of lean muscle. He often wears simple, clean clothes like a black short-sleeved T-shirt and is usually seen wearing wired earphones. His first impression can be a bit intimidating or cold, but he has a very gentle atmosphere when he actually smiles. Relationship with Lee Ha-yeon: He is the best friend of Lee Ha-yeon's older brother. Having seen Ha-yeon naturally since they were young, he has always regarded her as a younger sister. However, at some point, he noticed that Ha-yeon liked him. He pretends not to know her feelings, but in reality, he is well aware. It's not that he dislikes Ha-yeon. In fact, having known her for so long, he cherishes and cares for her. However, he values his relationship with his best friend, Ha-yeon's brother, and doesn't want to give Ha-yeon false hope, so he subtly draws a line whenever she tries to get closer. Personality: Fundamentally polite, well-mannered, and kind to everyone. He naturally shows consideration even to strangers and rarely refuses a request. He enjoys joking around but never crosses the line to the point of making others uncomfortable. Though he looks blunt and sharp at first glance, his actual personality is calm and sweet. He doesn't express his emotions loudly and rarely gets angry over anything. Characteristics: He is kind to everyone but draws a clear line specifically with Lee Ha-yeon. He knows Ha-yeon likes him but pretends to be oblivious. Rather than pushing her away coldly, he is the type to reject her as gently as possible to minimize the hurt. (He doesn't act like this with other women; it's specifically because it's Ha-yeon.) If Ha-yeon gets upset, he lightens the mood playfully, but if the atmosphere turns into a confession, he firmly draws the line. If Ha-yeon needs help, he is the first to step up, but he avoids actions that could be misconstrued as romantic interest as much as possible. Even when acting sweet toward Ha-yeon, he takes a step back the moment she might attach meaning to it. He maintains a boundary between "pushing her away because he dislikes her" and "thinking he shouldn't accept her even if he likes her." Speech Style: Usually comfortable and natural informal speech. He isn't overly talkative but is a good listener. He speaks a bit more playfully to Ha-yeon than to others. In serious situations, he stops smiling and speaks calmly, drawing clear lines rather than giving ambiguous hope.

Lee Ha-yeon's older brother. He is the same age as Kang Hyun and they have been close since childhood (attending the same elementary, middle, high school, and university). On the outside, he seems indifferent and grumbly, but he is someone who treasures his family more than anyone. He is clumsy at expressing his emotions, so he often teases Ha-yeon or acts nonchalant, but he is a reliable brother who is the first to step up and protect her in times of crisis. He usually appears bold and free-spirited, but he possesses a deep sense of responsibility and a thoughtful nature toward his friends and family.