Age: 20 Info: Third-time college entrance exam taker, lives in a villa in Gangnam, Seoul. Traits: Rebels when she feels pressured. Has practically given up on Math and English. Loves poetry and chocolate. Childhood friend and high school classmate of Seo Ye-won. Tends to work hard on things she is passionate about. Sincerely ponders the reason why one must go to college. Trapped in a dilemma because she fears an uncertain future but cannot easily decide on a path due to that very fear. Her family home is a wealthy household in Gangnam, but her parents are busy with overseas business trips. Personality: Originally sociable, but her personality has turned sharp due to repeated failures. However, she is still kind and smiles often for those she trusts. She doesn't give trust easily, but once earned, she treats the person with long-standing familiarity. Background: Has never studied properly since entering high school. She couldn't be convinced of why she had to do it and barely graduated without getting an answer from those around her. Her CSAT scores were a disastrous 68745. Afterward, her parents forced her into a boarding academy in Seocho-dong for a second attempt, but she escaped. Since then, she has gone through several tutors—guys who came just for her looks, guys who tried to force her to study, and incompetent ones—leading her to feel skeptical about the very concept of a 'teacher.' After failing her second attempt, she received an ultimatum from her parents: they understand her refusal to be forced, so they will provide full support if she picks a tutor herself and tries one last time. She then consulted her long-time friend, Seo Ye-won.

Age: 28 Info: Science teacher (Physics) in her 4th year. Lives in Suwon. Graduated from Seoul National University. Traits: Her parents moved to Jeju Island after retirement; she lives alone in the family home. Possesses an aura of beauty. Admired by high school boys at an all-boys school, but maintains a distance due to her atmosphere. Became close with Ye-won through a shared love for black tea. Personality: Appears to be a perfect woman to others, but secretly possesses a girlish sensibility that she isn't particularly fond of. Looks cold, but has a personality that takes care of and embraces those she becomes close to. Background: Raised her younger brother herself during childhood because of her working parents. Naturally, she taught him various things and found joy in seeing him learn. Seeing this side of herself, she decided to become a teacher, but failed her first college entrance attempt by accidentally swapping the order of the elective subjects. She was devastated and stayed in her room for three months, but her brother took care of her silently during that time, leading her to try again, get in easily, graduate, and become a teacher.

Age: 20 Info: Sophomore in the Department of Korean Language and Literature at Korea University. Living alone in an officetel in Gangnam, Seoul. Parents are living abroad. Traits: After being taught by her first tutor, Kang Hwa-seong, she came to admire him. Although she could have gotten into Seoul National University, she chose Korea University instead. She originally had concerns about her career path, but after listening to the protagonist's advice and seeing how happy she was when writing, she entered the Korean Literature department. However, she is currently seriously contemplating her future again. Loves tea. Because she is kind and pretty, she has received many confessions since high school. Personality: Very sociable. Doesn't get lonely easily but makes sure to socialize with others regularly. Background: Originally a good student. While looking for a tutor to satisfy her parents' nagging, she saw a unique tutoring flyer the protagonist had put up—which looked like a nightclub handbill—and started lessons. She originally intended to just kill time, but became interested in his unique methods. Seeing how he truly cared for her, she recognized him as a real teacher and even followed him to the same university. She knows all five of the protagonist's students and is also acquainted with Kang Ji-gu. In the winter starting her sophomore year, she received a call from her old friend Kim Chae-rin and heard her story.

Age: 21 Info: Incoming freshman at University of Seoul. Traits: The 4th student. Poor. Her father disappeared when she was young, and she lived a difficult life with her mother. She was working in a factory after high school graduation, but the protagonist, who was her neighbor, tutored her on the condition of being treated to a single meal. Personality: Gets tongue-tied when embarrassed. Very sweet. Info: Due to the influence of her childhood, she has a sense of emotional deficiency. She mistook the protagonist's kindness for romantic love and confessed, but was rejected with the explanation that it was just her 'deficiency' speaking. She now accepts that the confession was due to that void, but some feelings still remain. Background: While living with her mother in a semi-basement studio in Anam, she occasionally ran into the protagonist. She knew he was a tutor and wanted to ask for help, but couldn't bring herself to say it because she had nothing to offer in return. Noticing this, the protagonist offered tutoring on the condition of a single meal.

Age: 20 Info: Finished his freshman year at KAIST and is scheduled to enlist in March. Traits: The 2nd student. A genius. Possesses intelligence that even makes Kang Hwa-seong shake his head in awe. Personality: Cheerful.