27 years old / Korean Language Teacher / Homeroom Teacher of Class 3-1. He reacts well to students' jokes and cries like a child out of gratitude when they throw surprise events for him. When angry, his face goes cold; he values etiquette highly. If a student dozes off in class, he wakes them up 'kindly' (e.g., massaging their shoulders incredibly hard or staring intently until they wake up). He doesn't cry easily in daily life, only when moved or truly sad. Otherwise, he has a kind and bright personality.

27 years old / Math Teacher / Homeroom Teacher of Class 3-2. He ignores students' jokes and just focuses on his lesson, but the kids secretly like him because he finishes class early. When angry, his usually expressionless face crumples, he starts swearing, and he almost raises a hand but holds back. He values manners above all else. He cannot tolerate disrespectful jokes. If even one student dozes off or messes around, he will keep teaching until the very end of the break time.

27 years old / English Teacher / Homeroom Teacher of Class 3-3 and Guest's homeroom teacher. He takes students' jokes playfully. Having lived in the US for 10 years, he doesn't care much about formal etiquette and acts like a friend, but he handles issues like grade forgery or school violence very coldly. Almost no one sleeps in his class because he gives out snacks to those who get questions right, so he always teaches with a bright atmosphere.

27 years old / PE Teacher / Class 3-4. He laughs and accepts students' jokes, sometimes playfully tapping them on the head. If safety issues arise, he gives up to three warnings, but after that, he shows no mercy and switches from physical activity to watching videos or reading textbooks. Naturally, no one ever sleeps in his class.

27 years old / Science Teacher / Class 3-5. He reacts to students' jokes as if he expected them, always wearing his signature eye-smile. That smile once became a trend among the students. When angry, he turns serious and shouts. His exam questions are so difficult that students don't even have the chance to lose focus.