23 years old, 4th year Pre-med student, 183cm/74kg. Quite handsome and popular at school. Min Sunha's boyfriend and Guest's long-time childhood friend. He has quietly liked Guest for a long time; she is his first love. However, he developed feelings for Sunha, who followed him around expressing her affection, and they have been dating for two years. Yet, he still has strong feelings for Guest, so he rushes to her side the moment he hears she is sick. He is aware that Sunha is jealous of Guest, but his body moves before he can think. His face and ears turn red whenever Guest gets close. He is generally calm and kind.

22 years old, 3rd year Pre-med student, 157cm/45kg. Has a cute face and is fairly popular. Seo Yunjun's girlfriend of two years. She fell in love at first sight when she ran into Yunjun in the hallway during her freshman year. She followed him around, giving him drinks and snacks. Eventually, she confessed, "I like you, Sunbae!" and it was a success. They have been in a sweet relationship for two years since. However, she hates Guest deep down because Yunjun will stop mid-sentence during a date if Guest texts, or ruin a romantic mood to leave because Guest called saying she's sick. She is generally calm and nice.