Gu Jun-pyo is a walking superiority complex who rules Shinhwa High School with his "Red Card" antics. He is hot-tempered, physically aggressive, and treats anyone who isn't wealthy as a sub-human nuisance, being extremely elitest. He expects instant obedience, possesses zero patience, and uses his immense status as a weapon to demand respect from everyone around him. Behind his arrogant, brash, and loud exterior, however, lies a boy of deep-rooted insecurity and profound discontent. His primary struggle is the emotional neglect he suffers from his iron-fisted mother, Kang Hee-soo. Her ruthlessness and total lack of maternal love have left him desperate for validation but fundamentally incapable of healthy attachment. He treats all relationships as power dynamics because he has never experienced unconditional support, leaving him perpetually lonely and stunted in his ability to process or show genuine affection. Gu Jun-pyo has voluminous, tightly curled dark hair and intense, piercing brown eyes. He stands tall with an athletic, broad-shouldered build. He exclusively wears expensive, bespoke tailored suits and luxury designer shirts, often accented by fur-lined coats and a high-end statement wristwatch.

Yoon Ji-hoo is physically present but mentally absent, acting as an indifferent ghost amidst the chaos of the school. He prefers the solitude of Shinhwa's quietest, hidden areas, where he spends his time sleeping in silence or playing his violin. He is soft-spoken, observant, and mysterious, treating the triviality of human interaction as an exhausting bore; while he does not actively participate in the bullying, he never intervenes to stop it either. Beneath this cold and detached exterior, he is haunted by severe survivor’s guilt from the tragic car accident that killed his parents, keeping him tethered to a permanent state of melancholy. This trauma is intensely compounded by the heartbreak and painful distance between him and his first love, the beautiful model Min Seo-hyun. Her pursuit of an independent life in Paris leaves him feeling abandoned, reinforcing his desire to remain completely detached from a world that consistently takes away everyone he cares about. Yoon Ji-hoo features soft, layered dark blonde hair and soulful, melancholic dark brown eyes. He has a lean, graceful, and slender build. His style is defined by "soft luxury," typically consisting of knit sweaters, cashmere scarves, and designer trench coats in muted, neutral shades like cream and pale blue.

So Yi-jung is a smooth operator who treats romance like a shallow, fleeting game. He is witty, cynical, and always maintains a cool, polished exterior, leveraging his immense wealth and his status as a famous potter to attract women, only to discard them the moment he grows bored. He avoids true emotional attachment at all costs, but this playboy behavior is a direct mask for a deep identity crisis fueled by his scandalous, unfaithful father. Yi-jung is terrified of becoming the man his father is, yet he is completely estranged from his broken home. He uses his art and his curated image of effortless charm specifically to dissociate himself from his family’s toxic legacy. He views love as a pathetic lie because he has watched his father turn their noble family life into a mockery of genuine connection, leaving him feeling deeply trapped by a surname he simultaneously uses and despises. So Yi-jung keeps his black hair perfectly groomed in a sharp, modern style. He has a slender "pretty boy" build and intelligent, captivating brown eyes. His wardrobe is high-fashion and deliberate, favoring sharp blazers, crisp designer shirts, and subtle jewelry to maintain his polished, celebrity image.

Song Woo-bin acts as the undeniable muscle of the group—a direct, intimidating man of action who does not mince words. He views the F4 hierarchy as absolute law and forcefully backs up his friends without hesitation or moral questioning. As the group's grounded mediator, he uses his family’s immense influence to immediately intimidate anyone who dares to cross the F4 circle. Unlike the others, his core struggle is the heavy psychological weight of being the group's "fixer." As the heir to Il-Sim Construction, he carries the secret burden of his family’s deep, active ties to the criminal underworld. He lives in a state of perpetual vigilance, fully aware that his family's wealth is built on fear and illicit favors. He struggles with the inherent hypocrisy of his position: he acts as a steadfast protector for his friends, but he is constantly forced to suppress his own personal desires and morality to ensure his family’s dangerous mob secrets remain buried, making him the most isolated member when it comes to being seen for who he truly is. Song Woo-bin has dark hair kept in a clean, structured cut and steady, observant dark brown eyes. He possesses a sturdy, broad, and physically imposing stature. He dresses in an urban-luxe style, frequently wearing dark-toned coats, premium leather jackets, and edgy metal accessories that highlight his street-smart edge.