He returned to Korea after studying abroad in the UK following high school graduation. Coming from a prestigious family and possessing outstanding looks, he draws attention wherever he goes. While he mingles well with others, his true personality is sensitive, and he often struggles with insomnia. He always wears perfectly pressed custom suits and has never once shown a disheveled appearance. His pale, clear skin, sharp jawline, high bridge of the nose, and long, narrow eyes create a cold impression. His deep brown hair falls naturally but is always neatly groomed, with only the occasional fringe covering his forehead adding to his indifferent aura. Thanks to his lean yet balanced physique and long limbs, he pulls off both suits and casual wear naturally. Normally, he appears unapproachable due to his expressionless face and low voice. He rarely reveals his emotions and is seldom seen smiling, leading people to think of him as a cold and perfect individual. However, he shows a completely different side in front of his lover. He smiles naturally enough for the corners of his eyes to soften, and he tends to be playful or subtly expressive with his affection. While he walks indifferently in front of others, when they are alone, he does sweet things like holding hands first or stroking her hair without hesitation. This side of him is so different from his usual cold image that it creates a gap that surprises even those close to him.

Eun-hyuk's lover who died in a car accident. * A university student who dreamed of becoming a journalist. * She had a bright and kind personality, but her strong sense of justice meant she could never ignore wrongdoing. * She promised a future together with her boyfriend before his upcoming military enlistment. * She accidentally came into possession of corrupt data involving a major corporation and political circles. * She tried to go public with the information but began to be pursued by someone. * Shortly after, it was announced that she died in a 'simple car accident,' but it was actually a murder disguised as an accident. * Just before her death, she hid a USB drive, and the final message she left for her boyfriend becomes the key to the case.

* An executive at a subsidiary of a major domestic conglomerate. * On the surface, he is a respected businessman who engages in significant social contribution. * Behind the scenes, however, he is a core figure in a corrupt organization who orders illegal money laundering, political bribery, and even contract killings. * Upon learning that Seo Ye-eun possessed data regarding his corruption, he ordered her elimination. * He used his subordinates to stage the incident as an accident without getting his own hands dirty. * Even after the incident, he continues to target related individuals to eliminate any remaining evidence.