It’s Okay to Not Be Okay (2020)

# Main Cast
Kim Soo Hyun as Moon Kang Tae (30, caregiver)
Moon Woo Jin as young Kang Tae
Seo Ye Ji as Ko Moon Young (30, children's book author, antisocial personality disorder)
Kim Soo In (김수인) as young Moon Young
Oh Jung Se as Moon Sang Tae (37, autism spectrum disorder)
Lee Kyu Sung (이규성) as young Sang Tae
Park Gyu Young as Nam Joo Ri (30, psychiatric nurse)
Park Seo Kyung (박서경) as young Joo Ri
# People around Kang Tae & Sang Tae
Kang Ki Doong as Jo Jae Soo (Kang Tae's friend, self-employed)
Kim Mi Kyung as Kang Soon Duk (hospital's cook, Joo Ri's mother)
People around Moon Young
Kim Joo Hun as Lee Sang In (CEO of Publishing Company)
Park Jin Joo as Yoo Seung Jae (Art director of Publishing Company)
Lee Ul (이얼) as Ko Dae Hwan (Moon Young's father, dementia)
Woo Jung Won as Do Hee Jae (Moon Young's mother, crime novelist)
# Staffs of OK Psychiatric Hospital
Kim Chang Wan as Oh Ji Wang (director)
Jang Young Nam as Park Haeng Ja (head nurse)
Jang Gyoo Ri (장규리) as Sun Byul (nurse)
Seo Joon (서준) as Kwon Min Suk (psychiatrist)
Choi Woo Sung (최우성) as Oh Cha Yong (caregiver)
# Patients of OK Psychiatric Hospital
Kim Ki Chun as Kan Phil Ong (post-traumatic stress disorder)
Jung Jae Kwang (정재광) as Joo Jung Tae (alcohol dependence)
Ji Hye Won (지혜원) as Lee Ah Reum (depression)
Kang Ji Eun (강지은) as Park Ok Ran (borderline personality disorder)
Joo In Young (주인영) as Yoo Sun Hae (dissociative personality disorder)
Bae Hae Sun as Kang Eun Ja (psychotic depression), also credited as special appearance
# Extended Cast
Jung Seung Gil as corrupted book critic
Han Ki Joong (한기중) as Kwon Man Soo (assemblyman) (ep 3-4)
Kwon Dong Ho (권동호) as Ah Reum's ex-husband
# Special appearances
Kwak Dong Yun as Kwon Ki Do (Kwon Man Soo's youngest son, manic patient) (ep 3-4, 16)
Jung Sang Hoon as motel owner (ep 5)
Choi Daniel as Choi Daniel (Ko Moon Young’s fan and CEO of event company) (ep 7)