Dear X

Yoo-jung Kim

Baek Ah-jin

Young-Dae Kim

Yoon Joon-seo

Do-Hoon Kim

Kim Jae-ho

Kim Yi-Kyeong

Sim Sung-Hee

Kim Ji-yeong

Seo Mi-Ri

Kim Ji-hoon

Choi Jeong-ho

Shin Moon-Sung

Detective Park

Soo-bin Bae

Baek Seon-gyoo

Seo An Lee

Lim Seon-ye

Gi So Yoo

Baek Ah-Jin (child)

Kim Yu-Mi

Hwang Ji-Sun

Yul-Eum Lee

Im Re-na

Yul-Eum Lee

Im Re-Na

Jong-Hyun Hong

Moon Do Hyeok

Hwang In-Youp

Heo In-kang

Hwang In-Youp

Heo Ing Gang

Il-Woo Kim

Hong Soo-hyeok

Lee Woong-Jae

Heo In Mo [In Gang's younger brother]

Seo-hie Ko

Maid Kong (Do-hyeok's servant)