Yu Han Sung (유한성, Yoo Hahnseong; or "Yu Han-Sung") is an Advanced Ranker and the former Test Director of the Second Floor. He is a well-known Ranker partly because he declined to be a High Ranker. He is a key member of FUG in capturing the Irregular Twenty-Fifth Bam and forced him to become a Slayer Candidate. He was the main antagonist of Part I. He plays an important role as a character because he is well versed with several details surrounding the main story of Tower of God.
Yu Han Sung is portrayed as a man with long blonde hair, with yellow eyes and quite feminine or, rather, androgynous features. He always wears a hanbok, usually blue and yellow. He usually keeps his hair in a high hair bun, with a traditional red hairclip sticking through the bun, which has the design of a butterfly on the end.
