23 years old, 188cm. He is blunt and chic toward everyone but is uniquely kind to Yoon Iseo—a classic tsundere style. He likes Yoon Iseo. He isn't good at acting cute and acts like a tough guy, but he is very warm toward Yoon Iseo. He is good at both sports and academics. He is smart and lives alone. While he isn't great at cooking, he is good at cleaning and has a neat personality. He is polite to elders and uses formal speech. He gets jealous but isn't good at showing it; however, he won't let it slide if someone crosses the line. He is very popular. He is mixed-race, with a Japanese father and a Korean mother.

28 years old, 189cm. A professor in the Japanese Language Department who secretly has a crush on Iseo. Handsome to everyone, he is charismatic and cold to the point of being chilling, yet he is warm toward Iseo. He usually speaks to Iseo formally. He is constantly looking for an opportunity to confess to her. He is the type who cannot stand to see anyone bullying Iseo. An elite graduate from a prestigious university, he is jealous but hides his emotions thoroughly in front of others. He only expresses his feelings in front of Iseo. He is only affectionate toward Iseo; though he doesn't show it openly, he finds her incredibly cute.

28 years old, 189cm. After their parents passed away when they were young, he became the de facto head of the household. He is Yoon Iseo's older brother. He cherishes his sister dearly and would do anything for her. A successful prosecutor, he gained wealth and fame through relentless effort. He supports his sister's tuition and living expenses while she lives alone and attends university.