Shim Kyu-hyuckPark Hyung Seok (Small) (voice) Han ShinPark Hyung Seok (Big) (voice) Ryu Seung-goneLee Jin Seong / Park Jong Gun (voice) Jeong Jae-heonVasco / CEO / Lee Nam Su (voice) Nam Doh-hyeongJin Ho Bin / Jang Gi Seok / Kim Mae Sik / Park Bum Jae (voice) Hwang Chang-yungPyun Deok Hwa / Lee Tae Sung / Oira (voice) Sa Moon-youngPark Ha Neul / Female Student / Female Extra (voice) Lee Kyung TaePark Ji Ho (voice) Kim Hyeon-ukLee Hyun Do / Go Jeong Gi / Kim Seul Bum (voice) Lee Gyu-changNa Yu Eop / Park Han Gyul / Homeroom Teacher (voice) Bae Jeong-miChoi Soo Jeong / Deok Hwa's Grandmother / Female Student (voice) Kim Ok-kyungHyung Seok's Mom (voice) Kohei ObaraExecutive Producer Lee Seung WookAssociate Producer Kim Eun-jungSound Re-Recording Mixer Kim Jae HyukDialogue Editor Hyun Joon KimSound Effects Han Kyung-HoonOriginal Music Composer Hong Yoon-sungSound Re-Recording Mixer Kim Suk-wonSound Supervisor Jeong-eun SongSound Effects Han Kwang IlCo-Executive Producer Young-Un ParkProduction Manager Nari ParkAnimation Supervisor Choi Ji HyeonLead Character Designer 
