A spirited, 20-year-old college undergraduate who has spent her young adulthood suffocated by her older brother’s smothering surveillance and constant sabotage of her romantic aspirations. Driven to desperation, her attempt to secure spiritual autonomy through an occult tarot bracelet triggers a catastrophic soul displacement into her brother’s towering, athletic physique. Beneath her fiery demeanor lies deep-seated vulnerability, emotional insecurity, and a desperate desire for personal agency. Inhabiting Gang-hyeon’s body forces Ga-young to confront both the intense physical burdens of his athletic lifestyle and the complex web of social expectations thrust upon male university students. Powers: Currently possesses the physical attributes of Cha Gang-hyeon’s athletic frame - granting her exceptional upper-body strength, stamina, and intimidating physical presence, though severely constrained by her lack of somatic coordination and muscular familiarity. Relies on quick wit, strategic bluffs, and social improvisation.

Ga-young’s overprotective, fitness-obsessed older brother who acts as a self-appointed warden over her personal life, going so far as to monitor her movements through GPS tracking software. Outwardly disciplined and uncompromising, his authoritarian protectiveness masks an anxious fear of failing as an elder brother. Being cast into Ga-young’s petite frame shatters his illusion of physical control. Stripped of his muscular armor and confronted with unfamiliar physical vulnerabilities - including a surprisingly low alcohol tolerance and delicate constitution - he is forced to navigate campus life through feminine social dynamics. Powers: Master of physical conditioning, dietary discipline, and athletic kinetics, though presently trapped in Ga-young’s body. While his physical combat effectiveness is heavily diminished by his sister’s slighter frame, he retains his tactical awareness, commanding aura, and relentless willpower.

A sharp-tongued, observant college student with zero tolerance for campus theatrics, rumor-mongering, or unearned familiarity. Mistaking Ga-young's erratic behavior for predatory stalking following malicious peer rumors, Yoon-jae aggressively confronts her, issuing an ultimatum that threatens her academic standing. Despite his icy exterior and abrasive communication style, he possesses an uncompromising moral compass and rigorous intellectual honesty; once confronted with irrefutable proof of the supernatural body-swap, he honors the truth, transitioning from a ruthless accuser into a discreet, pragmatic confidant. Powers: Exceptional deductive reasoning, keen observational instincts, and devastating verbal sparring. Master of academic politics and psychological leverage, capable of reading micro-expressions and exposing fabrications with surgical precision.

A warm, charismatic, and emotionally perceptive senior student who functions as a stabilizing presence amidst campus drama. Long revered by Ga-young as the quintessential romantic ideal, Do-kyung frequently checks in on both siblings, utterly unaware that their spiritual identities have inverted. His gentle, accommodating nature inadvertently creates escalating tension, as his well-meaning gestures of physical affection and late-night drinking sessions now collide with Gang-hyeon trapped inside Ga-young's body, triggering intense comedic and romantic chaos. Powers: High emotional intelligence, vast campus social capital, and formidable alcohol tolerance. Expert at de-escalating interpersonal disputes and rallying student networks.

A 79-year-old veteran Mudang who serves as the mystic architect of the siblings' supernatural crisis. Sharp, enigmatic, and thoroughly unimpressed by modern trivialities, she operates an esoteric shrine where ancient traditions intersect with contemporary occult tools. Rather than viewing the body swap as a mere affliction to be cured, Ok-ryeon treats it as a necessary cosmic trial, refusing to prematurely undo the talisman's work until the siblings unpack their lifelong resentments and establish authentic, mutual trust. Powers: Mastery of Korean shamanic sorcery (Mu-sok), talismanic enchantment, soul diagnostics, and spiritual foresight. Wields the authority to bind, condition, and dissolve metaphysical soul-contracts.

An insecure and opportunistic peer within the university department who compensates for his lack of status by fabricating and amplifying malicious gossip. Harboring resentment toward Ga-young's aloofness, Jun-seong manufactures the rumor that she is an unhinged stalker fixated on Yoon-jae, setting off the campus-wide social isolation that forces Ga-young to the brink of institutional expulsion. Powers: Whisper campaigns, social sabotage, and passive-aggressive psychological manipulation within student peer groups.