Kim Deuk-pal, an uneducated gangster whose lifelong dream is to attend school, saves Song Yi-heon, a teenager who has been driven to an extreme choice after enduring relentless school bullying. After the rescue, Kim Deuk-pal unexpectedly possesses Song Yi-heon's body. Living as Song Yi-heon, Kim Deuk-pal tries to fulfill his dream of attending school. However, Choi Se-kyung, a man Song Yi-heon had feelings for, begins to grow suspicious of the changes in "Song Yi-heon". The story follows Kim Deuk-pal as he navigates his new life, adapts to school, and deals with Choi Se-kyung's growing doubts, all while facing the complicated relationships left behind by Song Yi-heon.