Still 17

Yang Se-jong

Gong Woo-Jin

신혜선

Woo Seo-Ri

Ahn Hyo-seop

Yoo Chan

예지원

Jennifer

왕지원

Kim Tae-Rin

Eugene Jung

Kang Hee-Soo

윤선우

Kim Hyeong-Tae

박시은

Woo Seo-Ri (young)

윤찬영

Gong Woo-Jin (young)

안승균

Jin-hyun

조현식

Han Duk-soo

Lee Do-hyun

Dong Hae-Beom

Kim Min-Seo

Acting

Im Byeong-gi

Gong Yong Hwan [Gong Woo Jin's father]

Park Hyun Jung

Kim Tae-rin's Mother