Yoo Ho-jeong

as Na-mi

Shim Eun-kyung

as Young Na-mi

Jin Hee-kyung

as Choon-hwa

Kang So-ra

as Young Choon-hwa

Koh Soo-hee

as Jang-mi

Kim Min-young

as Young Jang-mi

Hong Jin-hee

as Jin-hee

Park Jin-joo

as Young Jin-hee

Lee Yeon-kyung

as Geum-ok

Nam Bo-ra

as Young Geum-ok

Kim Sun-kyung

as Bok-hee

Kim Bo-mi

as Young Bok-hee

Min Hyo-rin

as Young Su-ji

Kim Si-hoo

as Young Joon-ho / Joon-ho's Son

Park Young-seo

as Young Jong-ki

Chun Woo-hee

as Sang-mi

Kim Hye-ok

as Na-mi's Mother

Jeong Seok-yong

as Jong-ki

Ha Seung-lee

as Ye-bin

Kim Yeong-ok

as Na-mi's Grandmother

Baek Jong-hak

as Nami's Husband

Jung Won-joong

as Na-mi's Father

Kim Won-hae

as Teacher

Kim Sae-byuk

as Class Monitor

Kang Rae-yeon

as Jong-ki's Girlfriend

Kim Ye-won

as Girls' Generation Leader

Ryu Hye-rin

as Girls' Generation Member

Lee Kyung-young

as Joon-ho

Hwang Choon-ha

as Past Detective

Bae Soo-kyung

as Gang High School Girl

Park Soon-cheon

as Woman in Past Picture

So Hee-jung

as Homeroom Teacher

Cha Tae-hyun

as Insurance Company Main Model

Lee Jun-hyeok

as President of Private Detective Office

Han Seung-hyeon

as Jung-mi's Older Brother

Yang Hee-kyung

as Jang-mi's Mother

Ju Jin-mo

as Sung-chan

Park Hee-jeong

as Young-jin

Go Joon

as Private Detective

Kwon Eun-soo

as School Broadcasting Club DJ

Choi E-sun

as Joon-ho's Friend

Sung Ji-ru

as Choon-hwa's Lawyer

Eom Hye-soo

as Sang-mi's Group

Ahn Soo-ho

as Judge

Yoon Jung

as Su-ji

Jun Yoon-ji

as Student Presenter at Festival

Choi Soo-im

as Bully Female Student

Yang Joo-ho

as Insurance Company Branch Manager

Lee Sang-ah

as Woman in Past Picture

Lee Seung-heon

as Joon-ho's Friend

Kang Ji-won

as Su-ji's mother