Shim Eun-kyung
Young Na-mi
Kang So-ra
Young Choon-hwa
Kim Min-young
Young Jang-mi
Park Jin-joo
Young Jin-hee
Kim Si-hoo
Young Joon-ho / Joon-ho's Son
Park Young-seo
Young Jong-ki
Kim Yeong-ok
Na-mi's Grandmother
Baek Jong-hak
Nami's Husband
Jung Won-joong
Na-mi's Father
Kim Sae-byuk
Class Monitor
Kang Rae-yeon
Jong-ki's Girlfriend
Kim Ye-won
Girls' Generation Leader
Ryu Hye-rin
Girls' Generation Member
Hwang Choon-ha
Past Detective
Bae Soo-kyung
Gang High School Girl
Park Soon-cheon
Woman in Past Picture
So Hee-jung
Homeroom Teacher
Cha Tae-hyun
Insurance Company Main Model
Lee Jun-hyeok
President of Private Detective Office
Han Seung-hyeon
Jung-mi's Older Brother
Yang Hee-kyung
Jang-mi's Mother
Kwon Eun-soo
School Broadcasting Club DJ
Choi Yi-sun
Joon-ho's Friend
Sung Ji-ru
Choon-hwa's Lawyer
Eom Hye-soo
Sang-mi's Group
Jun Yoon-ji
Student Presenter at Festival
Choi Soo-im
Bully Female Student
Yang Joo-ho
Insurance Company Branch Manager
Lee Sang-ah
Woman in Past Picture
Lee Seung-heon
Joon-ho's Friend