Kim Yeong-hye is a married woman who suddenly decides to stop eating meat after experiencing terrifying dreams filled with blood and murder. Her shift to vegetarianism initially confuses her husband and enrages her strict family. As she loses weight and becomes increasingly withdrawn, she searches for safety in a world she perceives as violent. She focuses on her breasts as the only part of her body incapable of killing, exposing them to the sunlight in an attempt to distance herself from human brutality.

In-hye is Yeong-hye's older sister and the primary breadwinner for her own family. She runs a cosmetics shop while managing her household and raising her young son. Exhausted and burdened by responsibility, she endures an emotionally distant marriage to an artist. She tries to maintain familial stability and social acceptability despite her younger sister's sudden, concerning behavioral changes.

Mr. Cheong is Yeong-hye's husband, a man who prefers a conventional, unpretentious life. He relies heavily on his wife for domestic tasks like cooking and ironing. He becomes intensely frustrated when her sudden vegetarianism breaches social contracts and embarrasses him in front of his colleagues. He struggles to empathize with her emotional state, viewing her actions primarily through how they negatively impact his own routine and desires.

In-hye's unnamed husband is a mixed media artist who shares a workspace with other creatives. He relies entirely on his wife's income to support his artistic pursuits while spending hours away from home. He develops a consuming physical and artistic fixation on his sister-in-law after learning she possesses a blue Mongolian mark on her body, prompting him to plan a radical new video project.

The strict father of Yeong-hye and In-hye. He demands absolute obedience from his family members and possesses a volatile temper. He views Yeong-hye's refusal to eat meat as a direct challenge to his authority at the dinner table, choosing to intervene physically to force her compliance.

The mother of Yeong-hye and In-hye. She attempts to resolve her daughter's physical decline through traditional means, bringing herbal remedies and foods like black goat extract to the hospital to restore Yeong-hye's strength. She largely follows her husband's lead during family disputes.

A fellow artist who shares a workspace with the Brother-in-law. He is unexpectedly recruited to participate in a highly unconventional video art piece involving body paint and nudity, a request that makes him highly uncomfortable.

A patient at the Ch'ukseong Psychiatric Hospital where Yeong-hye resides. The hospital pays her a small stipend to assist with looking after Yeong-hye's daily needs when the nurses are occupied.

The young son of In-hye and the Brother-in-law. He is primarily cared for by his hardworking mother and occasionally the neighbors, due to his father's frequent absences for artistic work.

A university professor and artist friend of the Brother-in-law. He creates conventional artwork and owns an art studio with excellent natural sunlight, which he allows his friend to borrow for a specific project.

The Brother-in-law's ex-girlfriend. She assists him by painting his body with large red flowers so he can participate in his own video project.