Lee Seong-Chul is the Director of the Ilsin Hospital, the hospital where Park Kyung-Hye stayed at while she was ill with Eternal Slumber. Although he appears in the webtoon, he is only named in the novel.
Seong-Chul is a balding old man with white hair on the sides of his head and a white mustache. As a doctor, he wears a simple white coat over a black tie and a white dress shirt.
Seong-Chul is a man of science, as he wished to keep Kyung-Hye around in order to find out how she was cured. However, he is not the type to stand up to power, as he immediately changed his mind after learning that Jinwoo, Kyung-Hye's son, was a S-Rank Hunter.
When Kyung-Hye suddenly woke up from Eternal Slumber after spending four years in a coma, Seong-Chul initially refused to let her go home so that he could figure out exactly how she was cured. However, after learning that her son Jinwoo was a S-Rank Hunter, Seong-Chul immediately reversed course and allowed her to be discharged. It's also implied that he chose not to inform the medical community about Kyung-Hye's miraculous recovery, as Yoo Myunghan and his staff had to do some digging to find out that she was cured.