The Devil’s Classroom

The Devil’s Classroom follows Kim Sang-an, a ruthless loan shark known for collecting debts without mercy. His life takes a dark turn when his younger sister, a school teacher, takes her own life after being brutally bullied by her students. Driven by anger and a desire for justice, Sang-an decides to take matters into his own hands.

To carry out his revenge, he becomes the homeroom teacher of the very students responsible for her suffering. Inside the classroom, he treats their actions as a “debt” that must be repaid, leading to a brutal and twisted teacher-student dynamic. As the story unfolds, the line between justice and cruelty begins to blur, creating an intense narrative filled with psychological tension, violence, and moral conflict.

Important Characters

• Kim Sang-an – A cold-blooded loan shark who becomes a teacher to take revenge on his sister’s bullies.
• The Students – A group of violent and manipulative teenagers responsible for the tragedy.
• Kim Sang-an’s Sister – A teacher whose death becomes the catalyst for the story.
• School Authorities – Individuals caught between justice and the chaos inside the classroom.

Major Arcs

• Tragedy Arc – Sang-an’s sister suffers bullying and dies, triggering his revenge.
• Teacher Entry Arc – He infiltrates the school as a homeroom teacher.
• Debt Collection Arc – Sang-an begins punishing students for their actions.
• Psychological Conflict Arc – The story explores morality, revenge, and consequences.