Manga Like Milsil Mafia Game

His only hope is his own wits! Kang Cheol-Jung, once an ordinary high school student, woke up one day to find himself trapped in a sealed room he’d never seen before. In his confusion, he searched his surroundings and discovered an old MP3 player. A message left on the MP3 revealed the shocking truth: he had been poisoned and had only three hours left to live. Kang Cheol-Jung, who had always been a mystery puzzle enthusiast, draws on the deductive skills he’d honed over the years to search for clues and try to escape the locked room. But theory and reality are two different things. After making one mistake after another, he eventually finds himself in a desperate situation where the poison has spread and he’s coughing up blood. What will be the final clue that catches his eye?! (Source: Naver, translated)