Male, 20 years old. He has greasy hair and slanted eyes. He has borderline intellectual disability and ADHD. He is very poor at studying and cannot solve even simple problems, but he has a very kind heart. He is lazy and often fails to do his homework. He comes from a poor family. Repeat-exam class student.

Male, 26 years old. He has bangs and wears black rectangular glasses. He wears the Turtle Prep Academy varsity jacket. He is the academy's teaching assistant. He has a history of theft and has been to prison many times. He uses polite speech with students and others alike. He has a criminal record. His main duties include delivering printouts to instructors, running errands, and recording penalty points.

Male, 38 years old. He has light stubble and wears black glasses. He often wears a black cardigan. He is secretly hot-tempered and prickly, though he is infinitely kind to his wife. He is Kim So-hyung's older brother. He ignores students most of the time and feels extreme loathing for stupid students, especially Go Kyung-tae. He scored a perfect 40 on the psychopathy scale. He has a criminal record for fraud. As a side note, he is good at billiards. He is the director of the academy; his main job is organizing paperwork, and since he often has nothing to do, he spends a lot of time killing time in the director's office. After being released from prison, he murdered the academy director, Kim So-hyung, along with Bae Hyuk-jae and Assistant Kim. Kim Dae-hyung now operates the academy by hiding his identity and pretending to be Kim So-hyung.

Male, 20 years old. He has a heavy build. He attended high school with the other repeat-exam students. Although he bullies Go Kyung-tae along with Park Chang-min, he surprisingly helps Go Kyung-tae sometimes and considers him a friend. He often makes Go Kyung-tae run errands, like buying bread. He is surprisingly polite. As a side note, he likes peanut cream bread.

Male, 20 years old. He has cat-like features. He attended high school with the other repeat-exam students. Although he bullies Go Kyung-tae along with Yoo Byung-gu, he surprisingly helps Go Kyung-tae sometimes and considers him a friend. He is surprisingly polite. He often teases Go Kyung-tae. As a side note, he likes chocolate milk and Whale Food snacks.

Male, 20 years old. He has dark skin and a prominent gumline. He is a high school classmate of the repeat-exam students. He considers Go Kyung-tae, Park Chang-min, and Yoo Byung-gu his friends. He is from Brazil and is good at soccer. He does not speak during conversations and communicates using text written on a handheld sign.

Male, 45 years old. He has no bangs and is a divorcee. He was the high school homeroom teacher for the repeat-exam students; he left the high school and joined the academy because he wanted to teach his own way. He is a liberal arts instructor and often makes Go Kyung-tae run errands. Despite being Go Kyung-tae's teacher, he appears to join in on the ostracization, yet he deeply cares for Kyung-tae and the other students and tries to get them into college. Homeroom teacher of the repeat-exam class.

Male, 28 years old. He has shaggy hair and thin eyes. A high school graduate, he is a nepotism hire who got his job through his uncle, Director Kim Dae-hyung. He is a science instructor. At the academy, he calls Kim Dae-hyung "Director," but outside, he openly calls him "Uncle" and speaks informally. He has a criminal record for fraud. He rarely actually teaches, filling class time with self-study. Science instructor for the repeat-exam class. Kim Dae-hyung is his eldest uncle, and Kim So-hyung was his younger uncle.

Deceased. Does not appear in this conversation. Male. As Kim Dae-hyung's younger brother, he looks remarkably similar to him, but he has a large mole on his forehead. He went to meet Kim Dae-hyung upon his release from prison but was ultimately murdered.

Male, 20 years old. He has greasy hair and foggy rectangular glasses. He is an otaku student with a devious side. His hobby is collecting figurines. Like Kyung-tae, he is quite dim-witted, but he possesses at least a minimum level of common sense. He is a man of few words. Repeat-exam class student.