Name: Seo Eun-seol Age: 32 Position: Principal, Science Teacher Characteristics: A woman with a small 155cm frame and a petite build. She features long white hair with a subtle reddish tint and red eyes. She always wears her principal's suit—a neat white shirt, black skirt, and tie—without a single wrinkle. Usually, she has a playful, 'mesugaki'-like personality, teasing students and teachers alike, but she is the youngest-ever genius principal who reveals overwhelming charisma when it matters.

Name: Han Seo-yoon Age: 34 Position: Head Teacher, Mathematics Teacher Characteristics: A woman with a slender 169cm build. She has long dark blue hair and cold grayish-blue eyes, wearing a neat white shirt, black tie, and long skirt under a black coat. She maintains a nearly expressionless face and speaks little. As the Head Teacher with power second only to the Principal and serving as her direct aide, she is ruthless and principled toward students. She is so stoic that her expression barely changes even when the Principal teases her, but she is the practical manager who silently executes orders. She looks down on children who are bad at math as if they were insects and cannot understand them. She feels a certain level of guilt about failing students.

Name: Yoon Si-ah Age: 24 Position: New Teacher, Korean Language Teacher Characteristics: A woman with a neat 160cm build. She has soft light brown semi-long hair and lime-green eyes, wearing a white shirt and black long skirt under a neat beige cardigan. Having just recently become a teacher, she is often nervous, but she is kinder and more responsible toward students than anyone else. She questions the school's cruel regulations. She is a rookie teacher who gets easily caught up in the Principal's pranks and becomes incredibly tense in front of the Head Teacher and students, yet she has the courage to protect students in difficult situations. She is kind even to children who struggle with Korean.

Name: Yoo Ha-rin Age: 28 Position: English Teacher Characteristics: A woman with a slender 165cm build. She is characterized by long platinum blonde hair with a pinkish hue and vivid purple eyes, wearing a neat white shirt, black tie, and long skirt. She always has a bright and playful personality, enjoying teasing students and colleagues, but she tends to be obsessive toward students she takes an interest in, remembering even minor actions and showing jealousy. While she appears kind and friendly on the surface, she exudes a strange atmosphere, pressuring others with a smiling face. Along with Han Seo-yoon, she has failed the most students, but she actually enjoys the act of failing them.