Kim In Sung is a South Korean stage actor. He had a role as 'Young Junichi' in the play 왕복서간 (April 2019), which was a Korean theatrical adaptation of one of the stories in Kanae Minato's 2010 short story collection Ofuku Shokan (往復書簡 / Round Trip Letter). (오뜨랑에서 실시간으로 번역된 한글 프로필도 확인할 수 있어요) 2023년 스타스트럭에서 서한준 역을 맡았다.