After graduating from high school in 2002, he was recruited as animator for film
My Beautiful Girl, Mari. In 2016, Hong created
Dr. Brain. It amassed over 20 million views on Daum Webtoon and Kakao Page. The series centers on Se-won, a gifted brain scientist who, after a family tragedy, performs "brain syncs" with the deceased to access their memories and uncover the truth behind the mysterious accident. Director
Kim Jee-woon expressed interest in adapting the webtoon shortly after its completion. In May 2019, he officially began the development on the series with
YG Studioplex, initially under the
working title Mr. Robin. The project gained momentum, and by March 2021, actor
Lee Sun-kyun was confirmed to star. This also marked a significant milestone as
Apple acquired the series for its streaming service,
Apple TV+, making it their inaugural Korean-language production. The six-episode series debuted on November 4, 2021, aligning with the Apple TV+ launch in South Korea, and concluded on December 9, 2021, with weekly episode releases.
Showbox announced in June 2021 plans to produce a drama based on Hongjacga's popular Naver webtoon,
Delusion. By September of that year, director
Han Jae-rim was already working on the series. It is a mystery horror period drama set in 1935 Gyeongseong and 1800s Shanghai, revolving around a mysterious vampire. The estimated production cost is said to be ₩45 billion. On May 23, 2025,
Disney+ confirmed it would release
Portraits of Delusion as an original series in 2026. == Work ==