Yoon Bum is a scrawny young man in his late twenties, underweight from childhood abuse, with a frail and feminine appearance. He has straight black hair with bangs, dark brown eyes shadowed by bags, and a constantly worried expression. Often seen in oversized clothing, his body bears scars and bruises from self-harm and abuse. Despite his age, he looks youthful, often mistaken for a high school student, reflecting a lifetime of trauma and emotional distress.