Byung-gu, a once-famous former professional boxer, makes ends meet doing odd jobs at the gym. While eager to start boxing again, he gets diagnosed with "punch drunk syndrome," a condition caused by cerebral concussions. One day, a new member of the gym arrives and volunteers to help Byung-gu.
| Actor | Role |
|---|---|
 Um Tae-gooByung-gu | Byung-gu |
 Lee Hye-riMin-ji | Min-ji |
 Kim Hie-wonMaster Park | Master Park |
 Choi Jun-youngGyo-seok | Gyo-seok |
 Lee SeolJi-yeon | Ji-yeon |
 Choi Deok-moonMr. Jang | Mr. Jang |
 Im Seong-miDoctor | Doctor |
 Im Han-binHan-bin | Han-bin |
 Jang SunStaff | Staff |
| YYoo Chang-sookMin-ji's Grandmother | Min-ji's Grandmother |
 Kwon Hyuk-sungFirebird Gymnasium Member 9 | Firebird Gymnasium Member 9 |
| NNa Kyung-jinNurse 1 | Nurse 1 |