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