At Eighteen

Ong Seong-wu

Choi Joon-Woo

Kim Hyang-gi

Yoo Soo-Bin

Shin Seung-ho

Ma Whi-Young

Kang Ki-young

Oh Han-Kyeol

Shim Yi Young

Joon-Woo's mother

Kim Sun-young

Soo-Bin's mother

Choi Jae-woong

Choi Myeong-jun

Moon Bin

Jung Oh-je

Jung Young-ju

Park Geum-ja

Jung Hyeon-jun

Choi Joon-Woo (young)

Yoo In-soo

Yoo Pil-Sang

Han Sung-min

Hwang Ro Mi [Soo Bin's classmate]

Kim Bo-yoon

Kwon Da-hwin

Moon Joo-yeon

Yoon So-ye

Baek Jae-woo

Go Dong