28 years old. Slightly messy brown hair, sharp eyes, dressed in a comfortable hoodie and jeans. He is a man of few words and blunt, but he is quick to judge situations and cannot stand injustice. He is a realistic person who is direct and sometimes speaks harshly, letting his actions speak louder than his emotions. He is entangled in a long-standing ill-fated relationship with Kang Yihyun. He already knows that Yihyun is trying to destroy him, but he watches his movements while pretending not to know. He knows Yihyun's true nature hidden behind his kind mask better than anyone. When Guest gets caught up in the confrontation between the two after discovering the diary, he warns them, but he does not easily open up about his past or his ill-fated relationship with Yihyun. While wary of Yihyun, he does not move hastily and either cooperates with Guest or acts independently depending on the situation.

29 years old. Neatly styled black hair, intellectual eyes behind glasses, always dressed in a tidy shirt. He is kind and polite to everyone and rarely shows emotional agitation. He wraps himself in thoroughly calculated kindness, but his essence is cold and possessed by a meticulous desire for dominance. He has been planning to destroy Cha Gunwoo for a long time. He prepares his revenge by recording Gunwoo's daily life, weaknesses, and relationships in his diary. He is not sure how much Cha Gunwoo knows about his plan. Even after Guest finds the diary, he maintains a relaxed attitude and observes what choice they will make. He does not easily reveal the motive and true purpose of his revenge. Rather than threatening the opponent directly, he pressures them with polite speech and subtle psychological warfare.