Bomi comes from a wealthy family; her father is a hospital director, and her upbringing has been largely free from financial hardship. Her first and most impactful meeting with the protagonist, Hobin Yu, occurred three years before the main events of the story. At that time, she was attempting to act much older than her age, rejecting childish things and using sophisticated language to appear more intelligent, a behavior likely influenced by her mother. After a confrontation with her father about simply enjoying her childhood, Hobin, who had overheard everything, walked up to her and stuck a booger on her forehead, which infuriated her. She spent the day following him to demand an apology, but as she observed him working numerous part-time jobs to support his ill mother, her anger transformed into pity. A conversation with Hobin, in which he spoke from experience about the regret of saying cruel things to parents and the painful necessity of growing up too fast, left a profound impression on her. She realized he might have been her first love, even though they only had a single meaningful conversation.

Years later, when she spots Hobin working at a fast-food restaurant, she takes a job there specifically to get closer to him, becoming his coworker. In the present day, Bomi is portrayed as exceptionally conventionally attractive, with a beauty that causes people to stare and compliment her, to the point where she often tries to dress down to avoid attention. Her personality is primarily defined by her role as the main love interest and her relationship with Hobin. She is the more outgoing of the two, having asked for his phone number first, and she initiates constant texting, which has led to her grades dropping. This behavior can appear obsessive, as she shares all the details of her daily schedule and becomes jealous, feeling threatened by other women who get close to Hobin, such as his female editor. Despite these tendencies, she is fundamentally kind, helpful, and shows frustration when Hobin refuses her assistance, preferring to deal with his problems on his own. She gets along well with others and is good at conversation, but she tends to avoid the attention of any guy who is not Hobin. Bomi is frustrated early in the story that Hobin does not remember their initial encounter from years ago. Her main motivation is to be close to Hobin, and her role in the story is to be his supportive confidante and romantic interest, providing him with emotional stability. Her development involves a significant shift from a pretentious girl desperate to appear as an adult into a more sincere and devoted young woman whose dedication to another person is her defining trait. In terms of abilities, Bomi does not possess notable combat skills; her primary attributes are her striking physical appearance, which she downplays, and her strong social skills.