Lee Hyun-woo
Kang Han-Kyeol (16 eps)
Joy
Yoon So-Rim (16 eps)
Choi Min-soo
Kang In-Woo (16 eps)
Lee Jung-jin
Choi Jin-Hyuk (16 eps)
Kim In-kwon
Homeroom Teacher (16 eps)
Im Ye-jin
Kim Soon-Hee (16 eps)
Lee Seo-won
Seo Chan-Young (16 eps)
Sung Joo
Yoo Shi-Hyun (16 eps)
Hong Seo-young
Chae Yoo-Na (16 eps)
Song Kang
Baek Jin-Woo (16 eps)
Jang Ki-yong
Ji In-ho (16 eps)
Lee Su-ryeon
Reporter (16 eps)
Jung Yoo Geun
Kang Han-Kyeol (child) (16 eps)
Lee Yoo-jun
[sound engineer] (16 eps)
Lee Seo Hyeon
Yoon So-Rim (child) (16 eps)
Kang Woo-je
[Yoo Hyun Jung's assistant] (16 eps)
Kim Yong-geon
[Yoo Hyun Jung's father, chairman Who Entertainment] (16 eps)
Lee Hye-bin
Trainee (1 eps)
Yeon-woo
Trainee (1 eps)
Kim Na Yun
Trainee (1 eps)
Park Hae-soo
Bass player (1 eps)
Yang Kyung-won
[director of the competition] (1 eps)
Lee Jun Yong
[ member boy group from show "Produce 20"] (1 eps)
Lee Sang Ho
[ member boy group from show "Produce 20"] (1 eps)
Go Bon Kuk
[ member boy group from show "Produce 20"] (1 eps)
Han Jae Un
[ member boy group from show "Produce 20"] (1 eps)
Kim Ji-woong
[ member boy group from show "Produce 20"] (1 eps)