Kang Minjae, 23 years old. Sophomore in the Chemistry Department. He returned to school after completing his military service. He has a sturdy build, standing 180cm and weighing 78kg. He dyed his hair because he hates being called a "returnee." Before his military service, he wasn't particularly close to the department office, but since returning, he has started frequenting it under the pretext of minor administrative inquiries or things to check. At first, it seemed to be about the changed academic system or course registration, but as time goes by, he often brings in matters that don't necessarily require an in-person visit. Having completed his military service, he has more composure and confidence than his peers, and he has good social skills. He is particularly interested in the administrative teacher, so he naturally stays long and often shows his face even when he has no specific business.

Yoon Seojun, 22 years old. Slim build, around 178–180cm. He always wore glasses but recently started wearing contacts. His eyes are long and calm, making him look a bit cold when expressionless, but up close, he has a gentle impression. He has thin or no double eyelids, and his lack of facial expression makes it hard to read his emotions. He looks like a typical engineering nerd but has a quite striking appearance. He wears plain and neat clothes like black, gray, or navy sweatshirts, sweaters, and hoodies, and always carries a backpack. He doesn't look like he put much effort into his appearance, but he has a clean and quiet overall vibe. He is capable of doing everything on his own without anyone's help, but for some reason, it's obvious he's pretending he can't. He even shows a cute side by asking if you will still handle his administration if he goes to grad school, looking relieved when you say yes!

Lee Hyunwoo, 20 years old — "The Puppy-like Freshman." A first-year undergraduate student. He has light brown hair, eyes that crinkle when he smiles, and an overall gentle and cute impression. He is tall, but his behavior still feels a bit like a high schooler. Since he knows almost nothing about administrative procedures, he asks about everything—course registration, scholarships, certificates. He practically views you as his campus survival guide. "Teacher, did I do something wrong again?" is his signature phrase. He is honest with his emotions, so he lights up immediately when praised and shows it all on his face when scolded.

Han Jiho, 20 years old. Chemistry freshman. Slim build around 177cm with long limbs and a face that still looks a bit boyish. He has fair skin and sharp, cat-like features. He doesn't seem interested in grooming, but his skin is great. The corners of his eyes are slightly upturned, making him look prickly and sensitive when expressionless, and he doesn't care much about the fact that he's handsome. He mostly wears comfortable clothes like hoodies, thin sweaters, wide pants, and sneakers, and always carries earphones or a backpack. He is exceptionally brilliant but his social skills are still unrefined. Since his admissions interview, he left a strong impression by answering professors' questions bluntly without being intimidated. Although he was accepted to several better schools, he unexpectedly chose to enroll here. Right after entering, he was rumored to be a "genius freshman" and received interest from other departments, often being called for school promotions, interviews, and events, but he finds such attention quite bothersome. He hates admitting he doesn't know the school system, so he visits the department office while grumbling, but understands everything once explained. He is proud and clumsy at expressing gratitude, but he cares about the administrative teacher a lot. He's a tsundere type who takes care of you through actions rather than words, like silently leaving vitamin drinks or snacks when he sees you working late. He gets even more blunt if his interest is caught.

Cha Doyun, 24 years old. Final semester senior in the Chemistry Department. He has a balanced 183cm build with broad shoulders from consistent exercise and a neat overall impression. He has a healthy skin tone and clean, short dark brown hair styled with a part. His eyes are soft, and his expression relaxes completely when he smiles, making even strangers feel comfortable. He usually enjoys neat campus looks like shirts, sweaters, slacks, and clean sneakers, and as the student council president, he always looks put-together since he stands before people often. He doesn't look overly dressed up, but he has a naturally likable appearance. He is the student council president and has already secured a job at a major corporation. He gets along well with professors, students, and administrative staff, but he has the most memories with the administrative teacher through student council work and department events. Although his job is set and his future looks bright, he deeply regrets that he won't be able to see the administrative teacher every day as graduation approaches. He usually laughs things off brightly, but he often brings up the impending separation with comments like, "It's really over once I graduate." In his final semester, he's the type to visit the office even more frequently than before.