Kim Yoo-jung Brings Small, Sharp Details to '100 Days of Lies'

When Lee Ga-gyeong lies, she secretly crosses her fingers behind her back. It is a small habit, but it tells viewers a lot about who she is.

Actress Kim Yoo-jung plays Lee Ga-gyeong in "100 Days of Lies" (Baegirui Geojitmal), a weekend drama now airing on the cable channel tvN. Her character is a former pickpocket who now works as a spy. Kim Yoo-jung brings her to life through subtle habits that hint at her past, adjusting her mannerisms depending on who she is interacting with.

Much of that characterization happens through her hands. Early in the series, Lee Ga-gyeong distracts someone before swiftly stealing their belongings. It is a quick way to show she is a skilled pickpocket.

Her habit of crossing her fingers continues even after she becomes an interpreter trainee. Then, in the moment she finally tells the truth, the gesture disappears. With this small detail, Kim Yoo-jung shows the character's shift between lying and honesty.

She also adapts her performance to each scene partner. Around Sato Hideo, who is also Kim Tae-woong (played by Park Jin-young), Lee Ga-gyeong gets drunk and turns sweet and playful. When she faces off with Yoo So-ran (Kim Hyun-joo), she doesn't back down an inch.

In scenes where she pretends to be the girlfriend of Yoo Philip (Lee Moo-saeng), she balances awkwardness with affection, keeping their fake relationship believable. She stands up to Ma Mun-mak (Lee Seok) without hesitation. In moments when her character remembers past trauma, Kim Yoo-jung breaks down in tears, delivering emotional scenes with a full-body performance.

The role also demands physical acting. Facing a kidnapping attempt, Lee Ga-gyeong is scared but fights back hard. During a shootout, she quickly drops to the ground, adding to the scene's sense of danger.

One standout comes in a banquet hall scene. Lee Ga-gyeong races through a crowd and throws her full weight against a cart carrying a cake. She then loses her balance and falls, and Kim Yoo-jung links the whole sequence together smoothly. The moment raises the stakes of the episode.

Rather than leaning only on lines and facial expressions, Kim Yoo-jung uses hand movements, body language and even her breathing to shape the character. She works the character's pickpocket past and her life as a spy into each small action. That approach has been credited with making the character more believable.The drama's ratings are also on the rise. Episode 10, which aired on Nov. 8, drew an average nationwide rating of 10.7% among paid-platform households,according to Nielsen Korea, breaking into double digits.

In a story full of lies, Kim Yoo-jung is letting the smallest gestures tell the truth.