Nano Mashine Wiki

Mun Ku (pronounced "Moon Gyu") is the female protagonist of Nano Machine. She is the granddaughter of Mun Yun, one of the elders of the Demonic Cult. She is a part of Cheon Yeo Woon's team during their stay in the Demonic Academy and his future first wife.


During the days within the Demonic Academy, she always wears a skin mask that resembles the face of her twin brother Mun Yu. But her true facial features has a pure white face with large, glittery eyes and small pink lips. Her beauty shined under the moonlight, further illuminating her slender physique.


Mun Ku was a descendant of the Dark Dragon Palm Clan (Demon Dragon in novel) 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. It is because she entered the Demonic Academy in order to increase her power and prove herself as well as to not join the heir-ship competition to avoid fighting against the Six Clans.

For the third test of the Demonic Academy, cadets are tasked to get the yellow name tags from instructors as well as to recruit members. Mun Ku successfully get a yellow name tag making her eligible to a group leader. Cheon Yuchan who is obsessed with talented martial artists, tried to recruit Mun Ku for the third time where she refused, that's when Yuchan ambushed her and managed to defeat her, taking her name tag as well as broke her leg. She tried to join other groups in order to get revenge but no one accepted her due to her broken leg, that's when he heard the incident where Cheon Yeo Woon defeated and cut off the arm of Cheon Yuchan.

She's one of the cadets that lined up and waited in order to join Yeo Woon's group, wherein her request to join was declined when she was asked if she wanted to join just for the third test or will side with him. She panicked as well as the other members of the group since Mun Ku is at the level of being a group leader. She insisted on asking for time to think that make Yeo Woon frown and asked Nano to analyze her facial muscles that leads to discovery of her skin mask as well as her gender being revealed as a girl, making her to pledge allegiance to Cheon Yeo Woon at that moment. After joining the group, she was welcomed wholeheartedly by the members such as Ja Wu-Min, Ko Wang-Hur, Baek Gi and Hu Bong.

After forming a new team, Cheon Yeo Woon met Mun Ku at the back of the Expert Training Facility. Mun Ku then asked Yeo Woon to promise her that he won't say to anyone about her being a girl. She then started to share her story by saying that she has a twin brother, Mun Yu. Her father was killed in a battle against the Forces of Evil when her mother was already pregnant with Mun Ku and Mun Yu. Due to her husband's death, her mother couldn't give birth to them properly because of her grief and sadness. Although Mun Ku had a normal birth, her younger brother was deprived of oxygen during his birth, which later on had a severe effect on his mental health. As a result, her brother became mentally impaired as he grew up. Mun Yun did not have another successor. Mun Ku was a girl and because of the fact that the Demonic Academy required every clan to send their children for training, he had no choice but to send Mun Ku (disguised as Mun Yu) to the academy. To avoid any suspicion from the other clans about Mun Yu being mentally impaired. As his Dark Dragon Palm Clan was a very powerful high ranking clan, many clans wanted to absorb the Dark Dragon Palm Clan into their own clan. If the fact that the sole successor of the Dark Dragon Palm Clan was actually mentally impaired was known by the other clans (especially the six clans) then they would try as hard as possible (even resorting to unfair means) to arrange a marriage between Mun Ku and their own Clan successors in order to absorb the Dark Dragon Palm Clan into their own ranks.