Bigak serves as one of the main antagonists in Part 1, and he is one that many characters, including Imae, fear. There quite a few chachaoongs who have sided with him because of this, whether they truly support him or not. His exact motives are unknown, but he has a particular interest in Imae and Yu Jin. He also seems to be the one who knows the most what is going on with Jack and the rise of the second generation chachaoongs.
Bigak has yellow eyes like Yu Jin, long black hair that fades to red at the ends, as well as a large, blade-like earring on his left ear. He often wears a coat with a fur lined collar when lurking about his base, but prefers black leather when out in public. He is frequently depicted with an unpleasant smirk, or a grin that borders on the insane.
Fans have noted similarities between his appearance and Yu Jin's awakened form.
While Bigak's presence tends to intimidate those around him, he seems somewhat lax in regards to his supporters and most of them seem to have a fair amount of freedom to move about as they wish. He usually has a calm exterior but he has described himself as lacking patience and self control; others refer to him as being unstable. He can be incredibly sly and cautious, and does not act rashly but is cruel to his followers, showing little patience for those who cross him or are no longer useful.
Regardless of his motives, he does not pick fights he knows he cannot win (or would be troublesome) such as with Jack or Cheoyong.
One of the rumors that had spread after Ei-Mae disappeared was that Bi-Gak had killed him. While this was untrue, there is still tension between the two as they apparently had some sort of confrontation in the past. When Bi-Gak met Yu-Jin for the first time, Bi-Gak felt as if they had met somewhere before even though it was technically their first time meeting. Yu-Jin's flashback revealed that the potential nature of this meeting was far from being on good terms and the unawakened Yu-Jin exhibited a great deal of apprehension during their meeting, though he wasn't sure why.
Bi-Gak has had unpleasant encounters with Chau Yoong in the past--possibly due to causing a number of unnecessary deaths. His reputation among most Chachaoong is not good and he's generally viewed as being unstable. Those who don't support him try to avoid any involvement with him.
Ei-Mae: The two have an unresolved conflict that goes back a few years. The nature of their conflict, and what exactly is going on between the two lies in not just the mystery of Ei-Mae's past, but Yu-Jin's awakened form as well. They do appear to hate one another a great deal.
Like all Chachaoong, Bi-Gak has the ability to materialize weapons from air. He has, so far, been seen wielding a whip-like weapon which he uses to both restrain and attack enemies. He is said to be as strong as, possibly stronger, than some of the Tals so it's unlikely he's been revealed fighting at his full potential yet.
Like several other Chachaoong, Bi-Gak also has the ability to 'seal off' areas to prevent normal Humans from entering them, as he did when he first met Yu-Jin.
Bi-gak has a Yongma called Ryu-Guheul. Ryu-Guheul has strips of prehensile cloth clipped to his clothing. This cloth can be manipulated to able to act swords, impaling people from far away as wel,l as to defend against multiple attacks at once. They are even capable of gripping and manipulating objects to at least some degree. Like Shadow and Shade, he doesn't speak and appears to be able to regenerate from what would normally be life-threatening injuries.