Jin Tae-hyun

Jang Seon-woo, a trainer

Adult Noh Se-bum

Kim Nam-joon

Do Gwang-woo

Roman Lee/Lee Ju-han

Min Jung-hyun

Kim Sang-soo

Jin Yong-seok

Ha In-woo

King Yeonsan

(cameo)

Gyoki Nam Da-reum as child Gyo-ki Seo Young-joo as teen Gyo-ki

Yoo Min-soo

Nam Joo-seung - Joo Ah-ran's lover. He is a person who has secrets of his own. Joo-seung works as a doctor during the day and works as a lounge singer at a jazz café at night. His father was the secretary of Mr. Shin, who the younger Nam now works for as the family doctor. He has no physical prowess, but has a strong eyesight, in addition to having a very strong charisma.

Kang Hyung-woo (Jung-woo's half brother)

Choi Choong-sik

Joon-ho, Kyung-min's college friend