Een bende van vijf geleid door Seok-Tae, kidnapt het babyjongetje Hwa-Yi en voeden het kind op als hun eigen zoon. Seok-Tae is een koude, maar charismatische leider, Ki-tae een geweldige autocoureur, Jin-seong een ideale planner, Beom-soo een wapenspecialist en Dong-beom een koude vechtjas. Van hen allen leert Hwa-Yi de kneepjes van het vak en wordt getraind tot een dodelijke moordenaar. Maar dan komt Hwa-Yi iets te weten dat hem op het spoor zet van zijn eigenlijke afkomst.
Nee, helaas is Hwayi: A Monster Boy nog niet beschikbaar op Netflix in Nederland.
| Visual Effects | 정도안 | Special Effects Supervisor |
| Editing | 김상범 | Editor |
| Art | Hyeon Chang-jo | Props |
| Costume & Make-Up | 황효균 | Special Effects Makeup Artist |
| Production | 이창동 | Executive Producer |
| Crew | 한정욱 | Stunts |
| Editing | Kim Jae-beom | Editor |
| Costume & Make-Up | 곽태용 | Special Effects Makeup Artist |
| Costume & Make-Up | Kim Jeong-ja | Makeup & Hair |
| Production | Lee Joon-dong | Executive Producer |
| Visual Effects | Sung Hyung-ju | VFX Supervisor |
| Production | Lee Dae-hee | Line Producer |
| Writing | Park Joo-suk | Writer |
| Crew | 정윤헌 | Stunts |
| Sound | 모그 | Original Music Composer |
| Costume & Make-Up | Ham Hyun-joo | Costume Design |
| Costume & Make-Up | Yumi An | Costume Design |
| Directing | 장준환 | Director |
| Production | 이동하 | Producer |
| Crew | Noh Nam-seok | Stunts |
| Costume & Make-Up | Lee Hee-eun | Special Effects Makeup Artist |
| Crew | Choi Bong-rock | Stunts |
| Crew | Lee Tae-yeong | Stunts |
| Crew | 송민석 | Stunts |
| Camera | Kim Sung-jin | Camera Operator |
| Camera | Cho Gi-hun | Key Grip |
| Camera | 김지용 | Director of Photography |
| Camera | Kim Jin-yeong | Still Photographer |
| Lighting | Cho Gyu-young | Gaffer |
| Sound | Lee Sung-jin | Sound Supervisor |
| Sound | Lee Seung-chul | Sound Supervisor |
| Art | 채경선 | Production Design |
| Sound | Han Myung-hwan | Sound Mixer |
| Costume & Make-Up | Hwang Hyun-gyu | Makeup & Hair |
| Art | Nam Seong-ju | Set Decoration |
| Directing | Kim Seong-sik | Script Supervisor |
| Directing | 양진모 | Script Supervisor |
| Sound | Jeong Ji-young | Sound Effects Designer |
| Writing | 장준환 | Adaptation |
| Art | Shin Yoo-jin | Production Design |
| Crew | 정두홍 | Fight Choreographer |
| Camera | 이모개 | Director of Photography |
