Kim Su-hoon

Director

Lee Ji-hyun

Romi (voice)

Jo Kyoung-i

Heartsping (voice)

Choi Nak-yoon

Heart King / Monster Truthping (voice)

Yeo Min-jeong

Belita / Girl (voice)

Hong So-young

Stella (voice)

Hong Bum-ki

Dr. Monziu / General Teenieping (voice)

Kim Ha-yeong

Marie (voice)

Ryu Seung-gone

Liam / Butler (voice)

Cho Hyun-jung

Truthping (voice)

Kim Eun-ah

Happying / Young Liam / Girl's Mom (voice)