Yor Briar works as an ordinary office clerk at Berlint City Hall but also leads a secret life as a Garden assassin under the code name "Thorn Princess"

At home, Yor typically wears a red off-shoulder sweater dress paired with black tights and brown-heeled ankle boots. The dress features a wide neckline, long sleeves, and a distinctive open-back design partially covered by an overlapping rear panel. She also wears a white headband and dangling gold spike-shaped earrings, accessories she retains across most of her appearances. When going outside, Yor usually wears a long beige (or pale pink) coat with black buttons over the dress. Her hair is parted and crossed over her head before being secured by the headband, forming two thick locks that fall below her chest.

Yor is a beautiful, graceful, and fairly tall 27 year old woman with a slender yet curvaceous frame and fair skin. She has long, straight black hair that reaches her mid-back, with short bangs framing her forehead, and distinctive upturned red eyes. Yor's beauty is frequently remarked upon by others. At Berlint City Hall, Yor wears the standard work uniform, consisting of a sleeveless vest and matching skirt over a white long-sleeved shirt, paired with black heels. As the assassin "Thorn Princess," Yor wears a form-fitting, halter-style black dress that exposes her shoulders and upper chest. The outfit includes a choker with square cutouts and a golden rose pendant, along with a red rose pattern lining the inside of the skirt. The front of the skirt is mid-thigh length, while the back extends below her knees. She also wears a pair of black thigh-high boots with matching square cutouts at the collars, rose emblems on the soles, and black fingerless gloves. Her headband is gold and adorned with a rose and two spike-like ornaments on each side, matching the design of her weapons. Yor wears red lipstick with this attire, and her hairstyle becomes more elaborate, styled into a braided updo wrapped around her head.

Despite her slim frame, Yor possesses monstrous superhuman physical strength. Her punches and kicks can generate visible air currents and she can easily pierce human skulls or throw her stilettos with enough force to break through wooden doors and impale targets beyond. She has climbed walls with her grip strength, broken portions of a skilled swordsman's weapon and even turned small objects such as buttons into lethal projectiles.

Yor's strength is so great that she often struggles to restrain it while posing as an ordinary civilian. She has accidentally sliced through a cutting board during cooking lessons. Yor must consciously hold back during sports and other recreational activities, often with limited success. Her strength is so difficult to suppress that even casual gestures can become dangerous. As she once broke two of her younger brothers ribs while hugging him during their youth.

Yor possesses extraordinary speed, agility, and athleticism, allowing her to move and react with remarkable efficiency in combat. Despite frequently fighting while wearing heels, she is capable of high-speed movement, rapid changes in direction, and complex acrobatic maneuvers. She can leap from great heights unharmed, perform parkour maneuvers with ease, and move quickly enough to intercept and eliminate enemy assassins before they can react. Yor has also demonstrated the ability to outrun a moving vehicle under unknown circumstances.

Her leg strength is particularly devastating. She can leap an entire floor while carrying two people, kick speeding cars off course, send grown men into ceilings, push heavy metal crates, and clear large debris while rescuing a civilian. In less controlled situations, her strength is occasionally portrayed in a more exaggerated manner, such as when she destroyed a carnival strength-tester with a casual swing, felled trees with dodgeballs, created craters in a court, and even launched a ball beyond the atmosphere.

Her reflexes are equally exceptional. Yor can intercept falling objects with precise kicks, catch and return a flowerpot in midair, dodge rifle fire, and evade sudden close-range attacks from highly trained opponents, including her mentor, the Shopkeeper. During her battle with Hemlock, she even caught a knife thrown at her between her teeth before immediately returning it as a projectile. Yor's coordination and body control are similarly refined. Even while suffering from injuries, she has demonstrated the ability to maintain precise balance and movement. She is also capable of catching multiple falling objects simultaneously with her hands and feet, highlighting the remarkable precision with which she controls her movements.

Yor possesses extraordinary endurance, resilience, and pain tolerance, allowing her to continue functioning despite pain and injuries that would incapacitate most people. She has repeatedly demonstrated this ability, including after sustaining a gunshot wound to her glutes, after which she returned home under her own power despite considerable pain.

Yor is capable of continuing to fight effectively even after sustaining injuries in combat. Quickly adapting her tactics rather than allowing the injuries to hinder her performance. Her remarkable pain tolerance enables her to remain focused and composed even while injured.

Yor's stamina is equally impressive and she also possesses an unusually high resistance to poisons, medicines, sedatives, and other incapacitating substances. She once consumed a cocktail containing blowfish toxins with only mild tingling and reduced pain sensitivity as side effects. She has also withstood inhaling poison gas potent enough to incapacitate a bear, while tranquilizers have little effect on her, even while intoxicated, seemingly doing little more than slightly easing her anxiety rather than rendering her unconscious.

Even medicines formulated for Yor may require special preparation, with Gympie remarking that the salve she prepared for her injuries was tailored to her unusually high resistance to both poisons and medicines. However, Yor's resistance is not absolute, as some of the poisonous plants and venomous creatures found in Ostania's southwestern forest are said to be capable of harming even her.

As a professional assassin, Yor is exceptionally skilled in close-quarters combat, combining refined technique with overwhelming physical power. While she favors powerful kicks, she is equally dangerous with her hands and is capable of rapidly adapting her fighting style to a variety of opponents and situations. Her combat training allows her to efficiently neutralize enemies through strikes, counters, grappling techniques, and attacks directed at vulnerable areas of the body. Yor has demonstrated the ability to contend with highly skilled opponents.

Yor's effectiveness does not depend on her weapons. Her assassination techniques are so ingrained that she is capable of using her hands as substitutes for her signature stilettos, employing thrusting attacks that mirror her usual fighting style. She demonstrated this when she split a pumpkin thrown by a thug using a hand strike and later used similar techniques against enemy assassins. During one confrontation, the force of her strike was sufficient to shatter a knife that had successfully intercepted the attack. These techniques have allowed her to defeat both ordinary criminals and trained assassins even when deprived of her weapons. Yor has also demonstrated using her legs as a substitute for her weapons, as she was able to block the attacks of an assassin's sword with her heels and kicks.

Her skill extends beyond direct attacks. Yor is capable of quickly restraining opponents through grappling and joint-manipulation techniques, as demonstrated when she effortlessly subdued Franky, who was impersonating an SSS officer, and forced him into compliance with a painful wrist lock

Yor is highly skilled in the use of her signature stilettos and other improvised throwing weapons. She demonstrates exceptional precision, accuracy, and control when employing her weapons, often targeting vital areas such as the head or major arteries in order to eliminate opponents as efficiently as possible. Yor's throwing ability is particularly notable, as she can accurately strike moving targets, intercept incoming attacks, and embed her weapons into solid surfaces with tremendous force. When deprived of her stilettos, Yor is capable of adapting nearby objects—or even her own earrings—as improvised throwing weapons. She has also demonstrated the ability to use her weapons defensively, intercepting incoming attacks and redirecting projectiles in the midst of combat.