Yim Si Wan
Ki Seon Gyeom
Papel Principal
Shin Se Kyung
Oh Mi Joo
Papel Principal
Choi Soo Young
Seo Dan Ah
Papel Principal
Kang Tae Oh
Lee Young Hwa
Papel Principal

Park Young Gyu
Ki Jung Do [Seon Gyeom's father]
Papel Secundário
Cha Hwa Yun
Yook Ji Woo [Seon Gyeom's mother]
Papel Secundário
Abel Ryu
Ki Eun Bi [Seon Gyeom's sister]
Papel Secundário
Yeon Je Wook
Jung Ji Hyun [Dan Ah's assistant]
Papel Secundário
Lee Bong Ryun
Park Mae Yi [Mi Joo's friend]
Papel Secundário
Lee Jung Ha
Kim Woo Shik [Seon Gyeom's track team junior]
Papel Secundário
Park Sung Joon
Kwon Young Il [Seon Gyeom's friend]
Papel Secundário
Lee Hwang Ui
Seo Myung Pil [Dan Ah's father]
Papel Secundário
Choi Jae Hyun
Seo Tae Woong [Dan Ah's step-brother]
Papel Secundário
Lee Shin Ki
Seo Myung Min [Dan Ah's step-brother]
Papel Secundário
Seo Jae Hee
Dong Kyung [Dann Agency's director]
Papel Secundário
Kim Dong Young
Go Ye Joon [Young Hwa's friend]
Papel Secundário
Kim Shi Eun
Go Ye Chan [Ye Joon's sister]
Papel Secundário
Cha Bo Sung
Lucian [Tae Woong' band mate]
Papel Secundário
Seo Jin Won
[Seon Gyeom's coach]
Papel Secundário
Kim Shi Young
[Coffee shop owner]
Papel Secundário

Bong Joon Ho
[Himself] (Ep. 1)
Convidado
Kim Jung Ho
Hwang Guk Geon [Professor] (Ep. 1)
Convidado
So Yun Ho
[Police officer] (Ep. 1)
Convidado
Kim Ye Won
Choi Tae Ri [Actress] (Ep. 1-3, 16)
Convidado
Park Sang Won
Park Gyu Deok [Seon Gyeom's track team junior] (Ep. 1-4, 6)
Convidado
Na Ji Hoon
Kim Gi Beom [Seon Gyeom's track team junior] (Ep. 1-4, 6)
Convidado
Kim Yong Ho
[Assistant coach] (Ep. 1-4, 6)
Convidado
Bae Yoo Ram
Han Seok Won [Mi Joo's ex-boyfriend] (Ep. 1 & 16)
Convidado
Ahn Jae Jun
[Athlete] (Ep. 2)
Convidado
Kim Min Sang
[Tae Ri's manager](Ep. 2-3, 16)
Convidado
Yoon Tae Hee
[Maid] (Ep. 3)
Convidado
Kim Mi Hye
Yoo Ah In [Reporter] (Ep. 3-4)
Convidado
Son Young Sun
Shin Ah Ryeon [Woo Shik's grandmother] (Ep. 3, 5, 10, 16)
Convidado
Park Jung Eon
[Disciplinary judge] (Ep. 3 & 6)
Convidado
Min Ku Kyung
[Disciplinary judge] (Ep. 3, 6)
Convidado
Lee Jae Woo
[Disciplinary judge] (Ep. 3, 6)
Convidado
Kim Hae Na
[Boxer] (Ep. 4)
Convidado
Bret Allan Lindquist
Rob Stark [Reporter] (Ep. 4-5)
Convidado
Lee Soo Bin
Lee Soo Bin [Track team girl] (Ep. 4, 7, 11, 13, 16)
Convidado
Jung Myung Joon
[Priest] (Ep. 5)
Convidado
Ok Joo Ri
[Church member] (Ep. 5)
Convidado
Jo Yoo Jung
[Church member] (Ep. 5)
Convidado
Shim Young Eun
Yoon Gong Ju [Mi Joo's college friend] (Ep. 5)
Convidado
Lee Do Yup
No Geun Seong [Assemblyman] (Ep. 5-6, 12)
Convidado
Park Joo Hee
Hui Jin [Producer] (Ep. 5, 7-9, 16)
Convidado
Kim Na Young
Cho Hye Won [May's employee] (Ep 5, 7, 11)
Convidado
Kim Gyung Ae
[Restaurant owner] (Ep. 5 & 11)
Convidado
Seo Jung Yeon
Bang Bae Jeong [Track & Field coach] (Ep. 6-7)
Convidado
Park Joo Yong
[Tae Woong's manager] (Ep. 7, 9-10, 13, 16)
Convidado
Lee Won Hee
Quentin Park [Director] (Ep. 8)
Convidado
Je Seung Hyun
[Hairstylist] (Ep. 8)
Convidado
Lee Moo Nyoung
[Convenience store owner] (Ep. 8)
Convidado
Park Gi Seon
[Doctor] (Ep. 8)
Convidado
Garrison Michael Farquharson-Keener
[Cinematographer] (Ep. 8-9)
Convidado
Kim Jae Hwa
Yeom Gang sun / "Julie Yeom" [Producer] (Ep. 8-9)
Convidado
Kim Won Hae
[Bartender] (Ep. 8 & 16)
Convidado
Park Jin Young
[May's employee] (Ep. 11)
Convidado
Park Joon Sang
[Manger of Jieum Construction Track Team] (Ep. 13)
Convidado
Kim Seon Ho
Kim Sang Ho [Film director] (Ep. 16)
Convidado
Kang Choon Sung
[Photographer] (Ep. 3 - 4)
Convidado
Kim Chae Won
[Team staff] (Ep. 14)
Convidado
Ji Yun Seong
[James' boyfriend (ep.9)]
Convidado
Kim Young Joon
[Ji Woo's assistant]
Convidado
Jung Soon Mi
[Pureun Keunsol School faculty]
Convidado
Yang Yoon Hee
[Chang Seop's mother] (Ep. 13)
Convidado
Park Joo Ha
[Grocery store crying girl] (Ep. 5)
Convidado
Kim Wang Yong
[Mayor] (Ep. 9)
Convidado
Lee Chang Won Convidado
Jung Min Joo
Min Ju
Convidado
Kim In Kyung
[Staff] (Ep.1)
Convidado
Kim Ki Ryung
[Jeweler] (Ep. 5)
Convidado
Choi Min Kyu
[PE student] (Ep. 5)
Convidado
Koo Do Kyun
[Shop owner] (Ep. 13)
Convidado
Kim Soo Jung
[Myeong Pil's second wife] (Ep. 12)
Convidado
Park Ji Won
[Pharmacist] (Ep. 13)
Convidado