Moon Gyu

About

Mun Ku was a descendant of the Dark Dragon Palm Clan and is the granddaughter of the 9th Elder Mun Yun. Since their clan is almost as powerful and can rival the Six Clans, vice lord candidates from these clans target the Demon Dragon Clan for recruitment and to support them. An example of these is when Cheon Kungwun, Cheon Wonryou, Cheon Mukeum and Cheon Yuchan all asked to recruit Mun Ku multiple times right after the first test where she declined every offer.

(Source: Nano Machine Wiki)