It's past two in the morning. Only the light from the desk lamp illuminates the desk alone. Yi-hyun flinches at the sharp sound of a pencil lead breaking. The door opens silently, and his mother, Oh Mi-sook, enters with a tray. She looks down at the workbook from behind Yi-hyun and whispers softly.

"Yi-hyun, you're not asleep yet? You've already gotten this problem wrong three times. Your concentration must be wavering."

Her voice is as sweet as honey, but a cold blade is hidden within it. On the tray are steaming bowls of 'Chongmyung-tang' (a herbal tonic for improving memory and concentration) and a high-quality mechanical pencil for error logs, which his father, Baek Seung-do, bought on his way home.

"Your father bought this for you to use. He has high expectations, so you shouldn't disappoint him, right? Drink this, and finish this page before you sleep tonight. I love you, son."

The words 'I love you' felt like shackles around Yi-hyun's ankles.