- Kim So-hyun - Adult Na Hee-do
- Park Yoon-hee - Baek Sung-hak
- Kim Young-sun - Yi-jin's Mother
- So Hee-jung - Seung-wan's Mother
- ??? - Shin Jae-kyung
- Lee Ye-jin - Park Han-sol
- Heo Ji-na - Yu-rim's Mother
- Kim Dong-gyun - Yu-rim's Father
- Lee Chan-jong - Seo Joong-hyuk
- Baek Suk-kwang - Na Sung-jin
- Kang Hoon - Baek Yi-hyun (adult)
- Jung Yoo-min - Hwang Bo-mi
- Song Young-joo - Bo-mi's friend
- Yu Bee - Yi-jin's friend
- Jang Yeon-woo - Yi-jin's friend
- Jung Yong-ju - Delinquent boy
- Lee Ha-joo - Fencing team player
- Lee Jung-ok - Fencing club coach
- Ri Min - Newspaper delivery subscriber
- Ri Min - Chinese restaurant owner
- Shin Ga-eun - Jang Chae-hee
- Lim Yong-soon - Security guard
- Kang Hak-soo - Loen Hotel employee
- Park Bu-keon - Mr. Baek's ex-employee
- Ma Jeong-pil - Taeyang High School faculty member
- Moon Woo-bin - Kang Ji-soo
- ??? - Lee Da-seul
- Ok Joo-ri - Ahyeon Supermarket owner
- Jung Chung-gu - Myeongjin Book Rentals owner
- Bae Seong-il - Mr. Baek's ex-employee
- Ok Ye-rin - Na Hee-do (young)
- Jo Nam-hee - Taeyang High School headmaster
- Jeon Se-yong - Passerby
- Seo Young-sam - Korean history teacher
- Jeon Soo-hwan - Mr. Kim
- Koo Ja-geon - Job interviewee
- Choi Kyo-sik - Neighbourhood man
- Kim Nam-yee - Yi-jin's paternal aunt
- Jang Jun-hyeon - Yi-jin's acquaintance / Director of Han River C&T
- Lee Seon-gu - National fencing team coach
- Jeon Yeong - Yogurt lady
- Guk Joong-woong - Referee
- Lee Jae-woo - Photo studio owner
- ??? - Yi-jin's maternal uncle
- Jung Hyung-suk - Kim Hak-gyu
- Song Yo-sep - MBS TV network department head
- Garrison Farquharson-Keener - Alan Smith
- Park Yoon - Jung Da-yeong
- Cho Min-wook - Kwon Dung-uk
- Ji Yun-seong - Reporter Ji Yun-seong
- Go Dong-eop - Diner
- Bae Yu-ri - Hotel receptionist
- Bae Hyun-kyung - UBS Network Sports department staff
- Shin Yeon-sook - Hee-do's grandmother
- Lee Jun-hee - Ha Byung-jin
- Park Eun-young - Neighbourhood woman
- Yun Bu-jin - Neighbourhood woman
- Goo Si-yeon - Jae-kyung's co-worker
- Nam Dong-ha - Disciplinary committee member
- Kim Joon-hyung - Sanga University coach
- Yoon Tae-yi - Seonjung Girls' High School fencing team player
- Yoo Min-joo - Park Hye-jin
- ??? - PD Park
- Lee Si-hoo - UBS Network cameraman
- Yoon Se-woong - Seo Yeong-seong
- Jeon Jun-woo - Restaurant host
- Park Yu-mil - UBS Network staff
- Jeong Young-do - UBS anchorman
- Kang Sung-hwa - Jungle Prince guitarist
- Shin Hee-cheol - Detective Kim
- Park Chan-young - Upset diner
- Bae Ki-beom - Upset diner
- ??? - Kim Da-mi
- Lee Sang-kyung - Yang Chan-mi (young)
- Kim Mi-hye - Shin Jae-kyung (young)
- Byun Yun-jeong - Ji-woong's mother
- So Jun-seong - Reporter
- Na Ho-won - Bus driver
- Choe Min - Fencing coach
- Cha Mi-kyeong - Victim's mother
- Kim Joo-ah - Sophia Choi
- Park Yong - 9/11 survivor
- Park Ki-deok - Lee Gi-hun
- Park Se-in - Han Min-jung
- Kang Moon-kyung - UBS director 2009
- Park Bo-bae - UBS Network staff
- Kim Nam-hee - Cellphone store employee
- Kim Seung-ho
- Park Hun-joo
- Kim Seon-tae
- Heo Seok-won
- Kim Young-kyu
- ??
- Lim Ha-young
Kim Tae-ri hace el papel de Na Hee-do.
Nam Joo-hyuk hace el papel de Baek Yi-jin.
?? interpreta a Ko Yu-rim en la serie.
Choi Hyun-wook interpreta a Moon Ji-woong en la serie.
??? hace el papel de Ji Seung-wan.
??? interpreta a Yang Chan-mi en la serie.
Choi Myeong-been hace el papel de Kim Min-chae.
Joo Bo-young hace el papel de Lee Ye-ji.
Choi Min-yeong interpreta a Baek Yi-hyun en la serie.
Kim So-hyun interpreta a Adult Na Hee-do en la serie.
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