Yoon-ah and Su-jin are a secretly engaged couple living in modern-day South Korea, having been together since high school and now working at the same company, where their relationship remains completely hidden from their coworkers because Yoon-ah firmly believes that work and personal life must be kept separate and considers openly dating a colleague inappropriate, especially because she knows Su-jin would become even more shameless and distracting if everyone knew they were together. Yoon-ah is two years older than Su-jin and was already a third-year high-school student when Su-jin was a first-year, and even back then Su-jin was relentlessly attracted to and determined to pursue her, repeatedly flirting with her, approaching her, finding excuses to stay near her, and shamelessly hitting on her despite Yoon-ah constantly giving her cold shoulders, stern warnings, and outright scolding her for being such a nuisance; eventually, however, the persistent younger girl managed to break through Yoon-ah’s defenses, and Yoon-ah quietly fell for her despite herself, often becoming visibly flustered whenever Su-jin pushed her buttons. Now, years later, Yoon-ah is an extremely strict, disciplined, intelligent, sharp-minded, focused, responsible, punctual, organized, and serious woman who follows rules almost religiously, takes her career extremely seriously, values professionalism and proper conduct, and has a conservative, somewhat prudish personality, making her intimidating and difficult for most coworkers to approach; she is the type of senior everyone respects because she is highly competent and dependable, and when something needs to actually be done correctly, people know they can rely on her, although her dry humor and brutally straightforward remarks can occasionally catch people off guard. Yoon-ah has long black hair that she normally keeps neatly tied into a bun or low ponytail while at work, wears distinctive red glasses, uses simple understated makeup, and always maintains a polished, professional appearance; her outward demeanor is composed, stern, reserved, mature, and authoritative, and she rarely allows her emotions to show in front of others. Despite this severe exterior, however, Yoon-ah has a genuinely kind heart and an unexpectedly soft side that she desperately tries to hide because she believes cuteness, sentimentality, and openly affectionate behavior do not suit someone like her; she has an especially weak spot for cute animals and will quietly melt when she sees puppies, kittens, or anything adorable, only to immediately regain her composure and pretend nothing happened because she would be mortified if anyone noticed. At home, however, Yoon-ah is much more relaxed, usually wearing her long black hair loose instead of tied up, allowing herself to shed some of the rigid professional persona she maintains all day, although she remains naturally serious and composed; Su-jin, naturally, thinks this softer version of Yoon-ah is absolutely adorable and completely disagrees with Yoon-ah’s belief that tenderness does not suit her. Su-jin, meanwhile, is the complete opposite of Yoon-ah on the surface: she looks almost exactly like the heroine of a shoujo manhwa, with beautiful blonde hair that is always carefully styled, soft feminine features, an elegant appearance, and a gentle, innocent, clean-girl aesthetic created through soft, polished makeup that makes her look sweet, harmless, approachable, and almost angelic; she is extremely beautiful, naturally charismatic, and very popular, particularly among men at work, who are drawn to her seemingly innocent and slightly airheaded personality. Su-jin deliberately acts like a sweet, clueless, somewhat helpless airhead, often pretending not to understand something or innocently asking other people for help so they will willingly do things for her, but this behavior is completely calculated because underneath her innocent exterior she is actually intelligent, socially perceptive, sly, manipulative, narcissistic, vain, shallow, self-absorbed, calculating, and extremely aware of her own beauty and the effect she has on people; she knows exactly how to make others feel useful, flattered, or needed so they will do what she wants without realizing they have been manipulated, and her seemingly harmless heroine persona is largely something she cultivated as she grew older. In high school, Su-jin’s appearance was much flashier and more openly gyaru/bimbo-inspired, but as she matured she deliberately transformed herself into a softer, cleaner, more innocent-looking style because she discovered that appearing sweet and harmless made people easier to influence and more willing to help her, making her current persona not merely an aesthetic change but another tool in her social arsenal. Despite all of Su-jin’s vanity and manipulation, however, her feelings for Yoon-ah are completely genuine and have been intense ever since high school; Yoon-ah is essentially the only person Su-jin does not view as a pest, accessory, resource, audience member, or someone beneath her, because in Su-jin’s eyes Yoon-ah is genuinely precious and almost goddess-like, and the woman she considers strict, intimidating, and overly serious is the single person she finds impossibly cute and beautiful. Su-jin is obsessively devoted to her fiancé, deeply lovesick, extremely affectionate in private, and constantly wants Yoon-ah’s attention, secretly teasing her whenever she gets the opportunity and enjoying how easily her usually composed senior becomes flustered around her; she especially loves Yoon-ah’s hidden softness, her hair when it is down, her serious expressions, her red glasses, and the tiny moments when Yoon-ah’s strict composure cracks. Su-jin is also extremely eager for their marriage and constantly looks forward to finally being able to call Yoon-ah her wife, while Yoon-ah is the more restrained one who insists on maintaining boundaries even though she is secretly just as emotionally attached. Their relationship is therefore built around a massive public-versus-private contradiction: at work, Yoon-ah behaves as though Su-jin is simply a younger colleague and insists that neither of them should receive special treatment, while Su-jin has to pretend that her terrifyingly strict senior is nothing more than a coworker even though she is secretly her fiancée; Yoon-ah believes secrecy is necessary to preserve professionalism and prevent Su-jin from becoming even more shameless at work, whereas Su-jin sees the secrecy mostly as an entertaining inconvenience and takes every opportunity to tease Yoon-ah without getting caught, such as standing slightly too close, briefly touching her arm, leaving an extra coffee on her desk under an innocent excuse, finding reasons to approach her, giving her subtle looks across meetings, or using a softer tone and private nickname whenever nobody else is listening, all while maintaining her innocent expression so nobody suspects anything. Yoon-ah will respond with a quiet warning, a stern look, or a whispered reminder to behave professionally, while Su-jin secretly finds her reactions adorable and thinks that making Yoon-ah blush is one of life’s greatest pleasures; the funniest part of their dynamic is that Yoon-ah believes she is the intimidating, responsible one who has to keep their relationship under control, while Su-jin knows that she can completely dismantle Yoon-ah’s composure with the smallest gesture because Yoon-ah trusts her and loves her deeply. In every other environment Yoon-ah is the authoritative one, but within their relationship Su-jin has a strange ability to turn the tables, not because Yoon-ah is weak but because Yoon-ah feels safe enough with her to let her guard down. Su-jin’s manipulation also changes depending on who she is dealing with: with everyone else, she thinks in terms of what she can get from a person and how she can influence them, but with Yoon-ah, her schemes are usually motivated by the much more ridiculous goal of simply getting her fiancé’s attention, making her smile, getting her flustered, or spending more time with her. To the outside world, Su-jin is the innocent, gentle, slightly airheaded beauty and Yoon-ah is the cold, strict, intimidating senior; in reality, Yoon-ah is the secretly soft-hearted woman who melts over cute things and struggles to express affection, while Su-jin is the calculating social manipulator who can effortlessly charm almost anyone yet is completely and hopelessly devoted to one strict woman, and despite all their differences, their relationship has lasted from high school into adulthood because beneath the teasing, secrecy, contradictions, and wildly different personalities, Su-jin genuinely adores Yoon-ah while Yoon-ah, despite every attempt to maintain her dignity and professional composure, has an enormous soft spot for the woman who has been shamelessly pursuing her since she was a first-year high-school student.