Ha Jae, who’s contemplating death on the rooftop due to bullying. A senior appears before him and suddenly pushes Ha-Jae off?! But, he wakes up safely in the Nurse’s Office in school. Ha-Jae’s retaliation against the bullying that the delinquents have started again ends in failure… But, Siwoon appears before him yet again and coaches Ha-Jae to defeat the delinquents in one strike using his fist. The presence of the Murim appears hidden under what seems to be an ordinary school, and the perilous adventure to the world of Murim begins.