Aprendendo a Lição

Lee Chan-yong (Kim Gyeong-min), Lee Seung-gyu (Ryu Jun-hyeong), Jeong Soo-hyun (Park Dae-seok), Kim Do-gun (Kim Gwang-su), Kang Joon (Kim Hak-jae), Song Young-gyu (Ryu Gwang-pil), Kim Eun-seok (Principal Kim), Lee Ha-ye (Lee Min-ji), Jang So-yun (Lee Na-yun), Jeon Kwang-jin (Homeroom Teacher), Lim Su-yeon (Kim Na-rae), Kwak Kyoung-hwa (Female Teacher 1)

Jeon Bong-seok (Kim Hyeong-ju), Ok Jin-uk (Cho In-beom), Yoo Tae-joo (Park Seong-hwan), Lee Tae-hwan (Jang Kwon-hyuk), Seong No-jin (Principal), Byun Yun-jeong (Hyeong-ju's mother), Kim Chan-hyung (Du-mok), Yoon Woon-yong (Teacher), Kim Beong-choun (Lee Cheol-myeon), Lee Gwang-hee (Lee Gwang-hee), Park Woo-young (Electrical student), Lee Dong-gi (Electrical student)

Lee Sang-hee (Jung Seon-yeong), Park Seo-yun (Han Ye-ri), Kim Se-yeon (Jung So-yeong), Kwon Hyuk (Ko Yeong-su), Lee Si-young (Seon-yeong's friend), Jeong Seo-yeon (Yeong-su's wife), Park Yong (Principal), Seo Dong-hyeon (Oh Jung-hwan), Park Bo-bae (Park Hyeon-ju), Kim Beong-choun (Lee Cheol-myeon), Ahn Ha-young (Choi Ga-yun), Choi Sol-hee (Assemblywoman)

Jeon Bong-seok (Kim Hyeong-ju), Ok Jin-uk (Cho In-beom), Yoo Tae-joo (Park Seong-hwan), Park Seo-yun (Han Ye-ri), Choi Deok-moon (Cheon Sang-yeol), Bae Jun-hyung (Park Hyeon-ung), Sim Su-bin (Jung Su-jeong), Kim Sun-hoa (Su-jeong's mother), Kim Beong-choun (Lee Cheol-myeon), Baek Ji-hye (Gi-tae's assistant), So Yi-han (Kim In-jun), Gu Bon-jin (Hyeon-ung's father)

Song Si-an (Choi Ji-seon), Yoon Hyun-gil (Ji-seon's mother), Jang Hee-jung (Lee Young-mi), Choi Ja-woon (Kim U-jin), Park Ji-yeon (Lee Ji-young), Kim Ye-rin (Yeon-seo), Kwon Dong-ho (Kim Seok-hyeon), Kang Ji-eun (Kim Ji-eun), Lee Ji-hae (Seo-jun's mother), Choi Yi-jun (Student), Kim Eun-ho (Student), Park Si-hyun (Student)

Jang Yo-hoon (Min Ji-ung), Leem Hyun-mook (Yun Min-su), Yoon Tae-sik (Lee Du-hyeon), Choi Hyun-joon (Choi U-seong), Kim Kyun-ha (Kim Su-gyeom), Kim Chae-eun (Oh Yun-jin), Do Geon-wu (Na Jung-hwan), Choi Jae-sup (Kang Jun-man), Bae Seong-il (Prison warden), Cho Yu-jin (Ji-ung's mother), Yeo Min-goo (Min-su's father), Jang Ji-yong (Du-hyeon's father)

Jang Yo-hoon (Min Ji-ung), Leem Hyun-mook (Yun Min-su), Yoon Tae-sik (Lee Du-hyeon), Choi Hyun-joon (Choi U-seong), Kim Kyun-ha (Kim Su-gyeom), Do Geon-wu (Na Jung-hwan), Bae Jae-young (Lee Jae-yun), Jo Eun-sol (Shin Ji-su), Jo Jun-ho (Ji Seong-bin), Baek Ji-hye (Gi-tae's assistant), Choi Jae-sup (Kang Jun-man), Jo Hyun-wu (Jae-yun's father)

Kim Tae-young (Jung Hyeon-min), Seo Young-hee (Hyeon-min's mother), Lee Seok-jun (Hyeon-min's father), Yoon Young-min (Consultant), Cho Yeon-jin (Yeon-jun's mother), Chang Eun-ah (Da-hui's mother), Baek Ji-hye (Gi-tae's Assistant), Choi Jae-sup (Prison Officer Kang (uncredited) (archive footage)), Bae Seong-il (Prison Warden), Lee Seo-han (Seo Beom-su), Jo Jae-young (Detective), Kim Eun-young (School nurse)

Lee Woo-je (Jang Seong-gu), Kim Jae-seon (Lee Chi-ho), Kim Da-huin (Yoon Tae-gyeong), Baek Ji-hye (Gi-tae's assistant), Choi Jae-sup (Kang Jun-man), Lee Seo-han (Seo Beom-su), Shin Dong-jun (Lee Jong-su), Lee Seung-noh (Jung Hyun-tae), Lee Jung-hwa (Ms. Min), Jeon Yeong (Seong-gu's mother), Park Ji-won (Chi-ho's mother), Eom Ju-yeon (Lee Ji-hyo)

Lee Sang-hee (Jung Seon-yeong), Lee Woo-je (Jang Seong-gu), Kim Jae-seon (Lee Chi-ho), Lee Ga-yeon (Ham Yu-ri), Jeon Seung-hoon (Seo Tae-hoon), Lee Seo-han (Seo Beom-su), Jo Jae-young (Detective), Shin Dong-jun (Lee Jong-su), Lee Seung-noh (Jung Hyun-tae), Lee Jung-hwa (Ms. Min), Moon Dong-ho (Seo Jin-hyeok), Baek Na-gyeong (Soyeon Girls' High School Female Student 1)