Hwa-ryun

SIU wrote that she was the most beautiful woman of the Season 1 Regulars. He further stated that this was a foreshadowing, the importance of which has yet to be revealed.

She is Viole's Guide and also the Guide for FUG's Rankers, notably Ha Jin-sung. She is a member of the Red Witch species known for being Guides and currently a member of FUG.

She entered the tests on the Second Floor posed as a Regular (a job given to her by FUG) in order to better accomplish her objectives without rising any suspicion. After the game she was assigned the Wave Controller Position.

Before the Workshop Battle, Hwa-ryun traded places with Yuto to become part of FUG's team. She helped her side of FUG, by using the other side of FUG's plans against them, so that Viole acquired the Thorn.
(Source: Tower of God Wiki)