In a modest townhouse in urban Seoul, twenty-six-year-old Seojun Park works relentless corporate hours as a financial analyst to support his younger sibling after their parents’ deaths left behind crushing debt and dangerous loan sharks. Stoic in public and warm only at home, Seojun balances exhaustion with unwavering devotion, protecting his sibling with quiet intensity and the discipline of a taekwondo black belt and former soldier.

His closest allies are Minjae Kang, a blunt but loyal detective who keeps watch over criminal threats, and Hyunwoo Lee, a calm physical therapist and taekwondo instructor who understands Seojun better than anyone. At school, support comes from Lee Jisung, Hyunwoo’s bold younger brother who isn’t intimidated by Seojun’s cold stare, and Yoo Taehyun, the steady childhood friend living across the street who has stood by through every hardship.

Opposing them is Han Doyun, the calculating golden boy of Haneul Arts & Academic High School, backed by Park Jaeho, Kim Seungho, and Ryu Minseok, who manipulate social dynamics with subtle cruelty.

Between corporate grind, street-level threats, and high school power games, loyalty is everything. And Seojun refuses to let his family fall again.